Co-reporter:Juanjuan Wu, Ruiyang Ma, Lin Hao, Chun Wang, Qiuhua Wu, Zhi Wang
Journal of Chromatography A 2017 Volume 1520(Volume 1520) pp:
Publication Date(Web):20 October 2017
DOI:10.1016/j.chroma.2017.09.012
•An organic polymer (PPTPA) was prepared via one-step self-polycondensation.•The PPTPA is first used as an adsorbent for the extraction of phenylurea herbicides.•The PPTPA showed satisfactory extraction efficiency for phenylurea herbicides.A hypercrosslinked organic polymer material (named as PPTPA) was prepared by a simple one-step self-polycondensation of triphenylamine. A series of characterization experiments, including N2 adsorption, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectra, and thermogravimetric analysis, were carried out to evaluate the morphology, structure and other intrinsic properties of the PPTPA. To investigate its adsorption performance, the PPTPA was used as the solid-phase extraction adsorbent for the extraction of phenylurea herbicides from water, milk and tomato juice samples followed by high-performance liquid chromatographic analysis. Under optimum conditions, good linearity for the analytes was observed in the range of 0.05–40.0 ng mL−1, 0.1-40.0 ng mL−1 and 0.5–40.0 ng mL−1 for water, milk and tomato juice samples, respectively. The established method also showed low limits of detection (S/N = 3) in the range of 0.008–0.01 ng mL−1, 0.01–0.03 ng mL−1 and 0.05–0.1 ng mL−1 for water, milk and tomato juice samples, respectively. The possible adsorption mechanism of the PPTPA towards the analytes was investigated, and the results demonstrated that the hydrogen bonding was the main interaction force between the PPTPA and the analytes. It suggests that the PPTPA can serve as a promisingadsorbent for the efficient pre-enrichment of organic compounds with more hydrogen-bonding donor sites.
Co-reporter:Shuaihua Zhang, Qian Yang, Xiumin Yang, Wenchang Wang, Zhi Li, Lihong Zhang, Chun Wang, Zhi Wang
Talanta 2017 Volume 166() pp:46-53
Publication Date(Web):1 May 2017
DOI:10.1016/j.talanta.2017.01.042
•A MOFs templated nanoporous carbon was synthesized and used as SPME coating.•The coating shows the advantages in extraction of pyrethroids.•The fiber possesses a long service time.A high-surface-area nanoporous carbon (NPC) has been successfully synthesized by using the metal-organic framework ZIF-90 as both the template and precursor together with furfuryl alcohol as a secondary carbon source. The prepared ZIF-90 templated NPC (ZIF-90-NPC) was then coated onto a stainless steel wire by a simple physical adhesion approach to prepare solid-phase microextraction (SPME) fiber. By coupling the ZIF-90-NPC coated fiber-based SPME with gas chromatography-microelectron capture detection (GC-μECD), the developed method gave a large enhancement factor (984-2869), low limit of detection (0.1–0.5 ng g−1) and good linearity (0.3–50 ng g−1) for the determination of some pyrethroid pesticides (bifenthrin, fenpropathrin, cyhalothrin, permethrin, cyfluthrin, flucythrinate, fenvalerate and deltamethrin) from different fruits and vegetables. The relative standard deviations (RSDs) for six replicate extractions of the pyrethroids by the ZIF-90-NPC coated fiber ranged from 4.3% to 8.0%. The recoveries of the spiked pyrethroids (5 ng g−1 and 20 ng g−1) from fruit and vegetable samples were in the range of 88.0–104.0% and 86.0–103.5% with the RSDs ranging from 4.8% to 12.9% and 5.0–10.8%, respectively. Besides, the ZIF-90-NPC coated fiber was stable enough for 100 extraction cycles without a significant loss of extraction efficiency. The method was successfully applied to the determination of the pyrethroids in fruit and vegetable samples.
Co-reporter:Shuaihua Zhang, Qian Yang, Zhi Li, Wenchang Wang, Chun Wang and Zhi Wang
Analyst 2016 vol. 141(Issue 3) pp:1127-1135
Publication Date(Web):11 Dec 2015
DOI:10.1039/C5AN02059J
A new solid-phase microextraction (SPME) fiber coating material, a zeolitic imidazole framework-67 (ZIF-67) templated nanoporous carbon, Co-NPC, was fabricated by one-step direct carbonization of ZIF-67 without using any other carbon precursors. The prepared Co-NPC was then coated onto a functionalized stainless steel wire by a simple physical coating method to prepare SPME fibers. By coupling the Co-NPC coated fiber based SPME with gas chromatography/micro-electron capture detection (GC/μECD), the developed method exhibited low limits of detection (0.07–0.45 ng g−1) and a wide linearity (0.30–50 ng g−1) for the determination of five organochlorine pesticides (OCPs) in vegetable samples. The method was applied to the analysis of cabbage, cucumber and celery cabbage samples, and the recoveries of the analytes were in the range of 87.9–103.9% with the relative standard deviations (RSDs) ranging from 5.1% to 10.4% (n = 5). Single fiber repeatability and fiber-to-fiber reproducibility values expressed as RSDs were in the range of 4.9–9.6% and 5.8–11.0%, respectively. The method was simple, convenient and feasible for the determination of OCPs in real samples.
Co-reporter:Shuaihua Zhang, Qian Yang, Wenchang Wang, Chun Wang, and Zhi Wang
Journal of Agricultural and Food Chemistry 2016 Volume 64(Issue 13) pp:2792-2801
Publication Date(Web):March 21, 2016
DOI:10.1021/acs.jafc.5b05831
A hybrid material of the zinc-based metal–organic framework-5 and graphene oxide (metal–organic framework-5/graphene oxide) was prepared as a novel fiber coating material for solid-phase microextraction (SPME). The SPME fibers were fabricated by covalent bonding via chemical cross-linking between the coating material metal–organic framework-5/graphene oxide and stainless steel wire. The prepared fiber was used for the extraction of five triazole fungicides from fruit and vegetable samples. Gas chromatography coupled with microelectron capture detector (GC-μECD) was used for quantification. The developed method gave a low limit of detection (0.05–1.58 ng g–1) and good linearity (0.17–100 ng g–1) for the determination of the triazole fungicides in fruit and vegetable samples. The relative standard deviations (RSDs) for five replicate extractions of the triazole fungicides ranged from 3.7 to 8.9%. The method recoveries for spiked fungicides (5, 20, and 50 ng g–1) in grape, apple, cucumber, celery cabbage, pear, cabbage, and tomato samples were in the range of 85.6–105.8% with the RSDs ranging from 3.6 to 11.4%, respectively, depending on both the analytes and samples. The metal–organic framework-5/graphene oxide coated fiber was stable enough for 120 extraction cycles without a significant loss of extraction efficiency. The method was suitable for the determination of triazole fungicides in fruit and vegetable samples.
Co-reporter:Weiqian Liang;Juntao Wang;Xiaohuan Zang;Chun Wang
Journal of Separation Science 2016 Volume 39( Issue 7) pp:1331-1338
Publication Date(Web):
DOI:10.1002/jssc.201501290
In this work, a porous carbon derived from amino-functionalized material of Institut Lavoisier (C-NH2-MIL-125) was prepared and coated onto a stainless-steel wire through sol–gel technique. The coated fiber was used for the solid-phase microextraction of trace levels of phthalate esters (diallyl phthalate, di-iso-butyl ortho-phthalate, di-n-butyl ortho-phthalate, benzyl-n-butyl ortho-phthalate, and bis(2-ethylhexy) ortho-phthalate) from tea beverage samples before gas chromatography with mass spectrometric analysis. Several experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimal conditions, the linearity existed in the range of 0.05–30.00 μg/L for green jasmine tea beverage samples, and 0.10–30.00 μg/L for honey jasmine tea beverage samples, with the correlation coefficients (r) ranging from 0.9939 to 0.9981. The limits of detection of the analytes for the method were 2.0–3.0 ng/L for green jasmine tea beverage sample, and 4.0–5.0 ng/L for honey jasmine tea beverage sample, depending on the compounds. The recoveries of the analytes for the spiked samples were in the range of 82.0–106.0%, and the precision, expressed as the relative standard deviations, was less than 11.1%.
Co-reporter:Xiaohuan Zang;Xi Zhang;Qingyun Chang;Sen Li;Chun Wang
Journal of Separation Science 2016 Volume 39( Issue 14) pp:2770-2776
Publication Date(Web):
DOI:10.1002/jssc.201600426
A sol–gel coating technique was applied for the preparation of a solid-phase microextraction fiber by coating the metal–organic framework UiO-67 onto a stainless-steel wire. The prepared fiber was explored for the headspace solid-phase microextraction of five nitrobenzene compounds from water samples before gas chromatography with mass spectrometric detection. The effects of the extraction temperature, extraction time, sample solution volume, salt addition, and desorption conditions on the extraction efficiency were optimized. Under the optimal conditions, the linearity was observed in the range of 0.015–12.0 μg/L for the compounds in water samples, with the correlation coefficients (r) of 0.9945–0.9987. The limits of detection of the method were 5.0–10.0 ng/L, and the recoveries of the analytes from spiked water samples for the method were in the range of 74.0–102.0%. The precision for the measurements, expressed as the relative standard deviation, was less than 11.9%.
Co-reporter:Lin Hao, Xing-Li Liu, Jun-Tao Wang, Chun Wang, Qiu-Hua Wu, Zhi Wang
Chinese Chemical Letters 2016 Volume 27(Issue 5) pp:783-788
Publication Date(Web):May 2016
DOI:10.1016/j.cclet.2016.01.021
In this work, a metal-organic framework derived nanoporous carbon (MOF-5-C) was fabricated and modified with Fe3O4 magnetic nanoparticles. The resulting magnetic MOF-5-derived porous carbon (Fe3O4@MOF-5-C) was then used for the magnetic solid-phase extraction of chlorophenols (CPs) from mushroom samples prior to high performance liquid chromatography–ultraviolet detection. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and N2 adsorption were used to characterize the adsorbent. After experimental optimization, the amount of the adsorbent was chosen as 8.0 mg, extraction time as 10 min, sample volume as 50 mL, desorption solvent as 0.4 mL (0.2 mL × 2) of alkaline methanol, and sample pH as 6. Under the above optimized conditions, good linearity for the analytes was obtained in the range of 0.8–100.0 ng g−1 with the correlation coefficients between 0.9923 and 0.9963. The limits of detection (S/N = 3) were in the range of 0.25–0.30 ng g−1, and the relative standard deviations were below 6.8%. The result showed that the Fe3O4@MOF-5-C has an excellent adsorption capacity for the analytes.A magnetic nanoporous carbon Fe3O4@MOF-5-C was prepared as the MSPE adsorbent for the extraction of some chlorophenols from mushroom samples.
Co-reporter:Wenchang Wang, Juntao Wang, Shuaihua Zhang, Penglei Cui, Chun Wang, Zhi Wang
Talanta 2016 Volume 161() pp:22-30
Publication Date(Web):1 December 2016
DOI:10.1016/j.talanta.2016.08.009
●Schiff base network-1 was synthesized and used as SPME coating.●The coating shows the advantage in extraction of phenols.●The fiber possesses a good high thermal stability and long service time.A novel covalent organic framework, Schiff base network-1 (SNW-1), was synthesized and used as a solid-phase microextraction (SPME) fiber coating material. The SNW-1 coated SPME fiber was fabricated by a covalent chemical cross-linking between the SNW-1 nanocomposite and a silanol-functionalized stainless steel wire substrate. Scanning electron microscopy and nitrogen isothermal adsorption results indicate that the new fiber coating exhibited a porous, homogenous surface with the Brunauer-Emmett-Teller surface of 668 m2 g−1. The prepared fiber was explored for the SPME of phenols from honey samples prior to their determination by gas chromatography-mass spectrometry. The developed method had large enrichment factors (136–816), low limits of detection (0.06–0.2 ng g−1), good linearity (0.1–100.0 ng g−1) and repeatability (<9.7%) for phenols. The recoveries for spiked phenols (1.0 ng g−1 and 10.0 ng g−1) in Wolfberry, Robinia and Codonopsis honey samples were in the range of 84.2–107.2% with the relative standard deviations ranging from 3.8% to 12.7%. The developed method was suitable for the determination of phenols from honey samples.
Co-reporter:Xiao-Jing Ding, Na Xie, Shan Zhao, Yu-Chen Wu, Jiang Li, Zhi Wang
Food Chemistry 2015 Volume 181() pp:207-214
Publication Date(Web):15 August 2015
DOI:10.1016/j.foodchem.2015.02.060
•A MEKC method with good accuracy and simple sample pretreatment was established.•Sample pretreatment played a key role for the assay of ten preservatives in food.•Satisfactory results were obtained with the PAPAS® proficiency test samples.An improved micellar electrokinetic capillary chromatography method (MEKC) for the simultaneous determination of ten preservatives in ten different kinds of food samples was reported. An uncoated fused-silica capillary with 50 μm i.d. and 70 cm total length was used. Under the optimized conditions, the linear response was observed in the range of 1.2–200 mg/L for the analytes. The limits of detection (LOD, S/N = 3) and limits of quantitation (LOQ, S/N = 10) ranging from 0.4 to 0.5 mg/L and 1.2 to 1.5 mg/L, respectively were obtained. The method was used for the determination of sorbic and benzoic acids in two FAPAS® (Food Analysis Performance Assessment Scheme) proficiency test samples (jam and chocolate cake). The results showed that the current method with simple sample pretreatment and small reagent consumption could meet the needs for routine analysis of the ten preservatives in ten types of food products.
Co-reporter:Shuaihua Zhang;Zhi Li;Chun Wang
Journal of Separation Science 2015 Volume 38( Issue 10) pp:1711-1720
Publication Date(Web):
DOI:10.1002/jssc.201401363
A novel solid phase microextraction fiber was prepared for the first time by using a sol–gel technique with hydroxypropyl-β-cyclodextrin-functionalized reduced graphene oxide as the fiber coating material. The results verified that the β-cyclodextrin was successfully grafted onto the surface of reduced graphene oxide and the coating possessed a uniform folded and wrinkled structure. The performance of the solid phase microextraction fiber was evaluated by using it to extract nine volatile aromatic compounds from water samples before determination with gas chromatography and flame ionization detection. Some important experimental parameters that could affect the extraction efficiency such as the extraction time, extraction temperature, desorption temperature, desorption time, the volume of water sample solution, stirring rate, as well as ionic strength were optimized. The new method was validated to be effective for the trace analysis of some volatile aromatic compounds, with the limits of detection ranging from 2.0 to 8.0 ng/L. Single fiber repeatability and fiber-to-fiber reproducibility were in the range of 2.5–9.4 and 5.4–12.9%, respectively. The developed method was successfully applied to the analysis of three different water samples, and the recoveries of the method were in the range from 77.9 to 113.6% at spiking levels of 10, 100, and 1000 ng/L, respectively.
Co-reporter:Xingli Liu;Chun Wang;Qiuhua Wu
Journal of Separation Science 2015 Volume 38( Issue 22) pp:3928-3935
Publication Date(Web):
DOI:10.1002/jssc.201500690
A porous carbon designated as MOF-5-C was prepared by directly carbonizing a metal–organic framework (MOF-5). The morphology and microstructure of MOF-5-C were characterized by scanning electron microscopy, N2 adsorption, and powder X-ray diffraction. The MOF-5-C retained the original porous structures of MOF-5, and showed a high Brunauer–Emmett–Teller surface area (1808 m2 g−1) and large pore volume (3.05 cm3 g−1). To evaluate its adsorption performance, the MOF-5-C was used as an adsorbent for the solid-phase extraction of four phthalate esters from bottled water, peach juice, and soft drink samples followed by high-performance liquid chromatographic analysis. Several parameters that could affect the extraction efficiencies were investigated. Under the optimum conditions, a good linearity was achieved in the concentration range of 0.1–50.0 ng mL−1 for bottled water sample and 0.2–50.0 ng mL−1 for peach juice and soft drink samples. The limits of detection of the method (S/N = 3) were 0.02 ng mL−1 for bottled water sample, and 0.04–0.05 ng mL−1 for peach juice and soft drink samples. The results indicated that the MOF-5-C exhibited an excellent adsorption capability for trace levels of phthalate esters, and it could be a promising adsorbent for the preconcentration of other organic compounds.
Co-reporter:Shuaihua Zhang, Zhi Li, Xiumin Yang, Chun Wang and Zhi Wang
RSC Advances 2015 vol. 5(Issue 67) pp:54329-54337
Publication Date(Web):05 Jun 2015
DOI:10.1039/C5RA05616K
A novel three-dimensional graphene (3D-G) coated fiber for solid-phase microextraction (SPME) was fabricated via a sol–gel coating method on stainless steel wires. The 3D-G was obtained by connecting graphene oxide (GO) sheets with Ca2+ and water molecules by hydrothermal treatment. Due to the π–π stacking and hydrophobic interactions between the 3D-G and the analytes, the 3D-G fibers showed high extraction efficiencies for the polycyclic aromatic hydrocarbons (PAHs). The developed method, which combined the 3D-G coated fiber-based SPME with gas chromatography-flame ionization detection, had large enhancement factors (842–2458), low limits of detection (2.0–10.0 ng L−1) and good linear range (10.0–1000.0 ng L−1) for the PAHs in water samples. Single fiber repeatability and fiber-to-fiber reproducibility were in the range of 4.7–8.8% and 6.4–11.9%, respectively. The recoveries of the analytes for the method were in the range from 76.5% to 102.6%. The fiber exhibited an excellent durability and can be reused more than 150 times without a significant loss of the extraction performance. The method was successfully applied to the determination of PAHs in water and soil samples.
Co-reporter:Xiaohuan Zang, Qingyun Chang, Mengying Hou, Chun Wang and Zhi Wang
Analytical Methods 2015 vol. 7(Issue 20) pp:8793-8800
Publication Date(Web):01 Sep 2015
DOI:10.1039/C5AY01578B
Graphene grafted magnetic microspheres were prepared and used as the adsorbent for magnetic solid phase extraction (MSPE) of bisphenol A and triclosan from water samples prior to their determination by gas chromatography-mass spectrometric (GC-MS) detection. A new customized ground-glass stoppered conical flask with a side tube was used for MSPE operations to simplify the separation of the magnetic adsorbent from the sample solution. The main experimental factors affecting the extraction recoveries of the analytes including the amount of adsorbent, pH of the sample solution, extraction time, salt concentration, desorption conditions, and derivatization conditions were investigated. Under the optimal conditions, a linear response was observed in the concentration range of 0.05–2.50 μg L−1 for bisphenol A and 0.10–5.00 μg L−1 for triclosan. The limits of detection (S/N = 3) were 10.0 ng L−1 for bisphenol A and 20.0 ng L−1 for triclosan. The established method was applied to the determination of bisphenol A and triclosan residues in environmental water samples with satisfactory results. The recoveries of the analytes using this method from lake, river, bottled and tap water samples were in the range from 93.9% to 104.3% (intra-day), and from 93.5% to 99.5% (inter-day) with the relative standard deviations varying from 2.1% to 5.8% (intra-day), and from 3.1% to 5.7% (inter-day).
Co-reporter:Shuaihua Zhang, Qian Yang, Zhi Li, Wei Gao, Chun Wang and Zhi Wang
Analytical Methods 2015 vol. 7(Issue 19) pp:8165-8171
Publication Date(Web):07 Aug 2015
DOI:10.1039/C5AY01585E
In this study, an ordered mesoporous carbon (OMC) with a large surface area, uniform mesoporous structure and large pore volume was synthesized by using Zeolite Socony Mobil-5 (ZSM-5) as the hard template and sucrose as the carbon precursor. The synthesized OMC-ZSM-5 was immobilized onto a stainless steel wire for the preparation of SPME fibers by a sol–gel coating method. The SPME of polycyclic aromatic hydrocarbons (PAHs) with the OMC-ZSM-5 coated fiber coupled with gas chromatography/flame ionization detection (GC/FID) provided large enhancement factors (738–2359), low limits of detection (LODs, 0.5–1.6 ng g−1) and good linearities (1.7–100.0 ng g−1) for soil samples. The relative standard deviations (RSDs) for single fiber and fiber-to-fiber reproducibilities were in the range of 4.6–7.9% and 6.1–10.2%, respectively. The developed method was successfully applied to the analysis of soil samples and the recoveries of the analytes for the method were in the range from 88.0% to 103.8%. The OMC-ZSM-5 coated fiber was stable enough for 160 extractions without a significant loss of extraction efficiency.
Co-reporter:Li Liu, Yunhui Hao, Xin Zhou, Chun Wang, Qiuhua Wu and Zhi Wang
Analytical Methods 2015 vol. 7(Issue 6) pp:2762-2769
Publication Date(Web):09 Feb 2015
DOI:10.1039/C4AY02990A
Magnetic ordered porous carbon (MOPC–ZSM-5) was synthesized using zeolite ZSM-5 as a template and sucrose as a carbon source. It was used as a magnetic solid-phase extraction adsorbent for the extraction of four neonicotinoid insecticides (acetamiprid, imidacloprid, thiacloprid and thiamethoxam) from river water and peanut milk samples prior to high performance liquid chromatography–ultraviolet detection. The calibration curves for the four neonicotinoid insecticides in the water samples showed linearity from 1.0 to 200.0 ng mL−1 for thiamethoxam, imidacloprid, thiacloprid and 0.5 to 200.0 ng mL−1 for acetamiprid. For the peanut milk samples, the linearity was observed in the range of 6.0–1000.0 ng mL−1 for thiamethoxam, imidacloprid, thiacloprid, and 3.0–1000.0 ng mL−1 for acetamiprid, respectively. The developed method has been successfully applied for the determination of the four neonicotinoid insecticides in river water and peanut milk samples, and a satisfactory result was obtained.
Co-reporter:Xiaohuan Zang, Guijiang Zhang, Qingyun Chang, Xi Zhang, Chun Wang and Zhi Wang
Analytical Methods 2015 vol. 7(Issue 3) pp:918-923
Publication Date(Web):24 Nov 2014
DOI:10.1039/C4AY02540G
A sol–gel coating technique was applied for the preparation of metal organic frameworks (MOFs)-based solid phase microextraction (SPME) fibers by coating MIL-101 onto stainless steel wires. The prepared fiber was explored for the headspace SPME (HS-SPME) of seven volatile aromatic compounds (VACs) from water samples followed by gas chromatography-mass spectrometric analysis. Several important experimental parameters, such as extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. Under the optimized experimental conditions, the developed HS-SPME method with MIL-101 coated fiber had a good linearity in the range of 0.05–50.0 μg L−1 for the analytes with the correlation coefficients (r) ranging from 0.9974 to 0.9988. Based on a signal-to-noise ratio (S/N) of 3, the limits of detection (LODs) for the seven analytes ranged from 1.0 to 5.0 ng L−1. Compared with two commercial SPME fibers, the laboratory-made MIL-101 coated fiber showed a higher extraction efficiency for the seven VACs. The established method was successfully applied for the determination of the VACs in real local tap and lake water samples. The recoveries for the method of the seven VACs at spiking levels of 0.1 and 5.0 μg L−1 were in the range from 76.4% to 116.1%.
Co-reporter:Qiuhua Wu, Ying Zhao, Chun Wang, Meng Sun, Xiaoxing Ma and Zhi Wang
Analytical Methods 2015 vol. 7(Issue 3) pp:901-908
Publication Date(Web):02 Dec 2014
DOI:10.1039/C4AY02423K
In this paper, a new sample preparation method based on mesoporous carbon reinforced hollow fiber liquid phase microextraction (MC-HF-LPME) was developed for the extraction of some phenylurea herbicides (chlortoluron, isoproturon, monolinuron and buturon) in river water and soil samples prior to high performance liquid chromatography-diode array detection. Mesoporous carbon was synthesized using MCM-41 as a template and sucrose as a carbon precursor. The as-prepared mesoporous carbon was characterized by SEM, TEM and nitrogen adsorption. Several important parameters that affect the extraction efficiencies, such as concentration of ordered porous carbon, fiber length, extraction time, sample solution pH, salt addition and stirring rate, were investigated and optimized. Under the optimum conditions, the linearity for buturon was in the range of 0.3–100.0 ng mL−1 and 5.0–300.0 ng g−1 for river water and soil samples, respectively. The linearity for the other three analytes was in the range of 0.2–100.0 ng mL−1 for the river water sample and 2.0–300.0 ng g−1 for the soil sample. The limits of detection (S/N = 3) of the method ranged from 0.05 to 0.1 ng mL−1 for the river water sample and 0.5 to 1.0 ng g−1 for the soil sample. The results indicated that the developed method is a simple, efficient and environmentally friendly method for the extraction and determination of phenylurea herbicides in river water and soil samples.
Co-reporter:Xingli Liu, Chun Wang, Qiuhua Wu, Zhi Wang
Analytica Chimica Acta 2015 870() pp: 67-74
Publication Date(Web):22 April 2015
DOI:10.1016/j.aca.2015.02.036
•Magnetic nanoporous carbon (MNC) was fabricated by direct carbonization of ZIF-67.•MNC is used as an adsorbent for the extraction of phenylurea herbicides.•The MNC adsorbent was efficient and reusable.Nanoporous carbon with a high specific surface area and unique porous structure represents an attractive material as an adsorbent in analytical chemistry. In this study, a magnetic nanoporous carbon (MNC) was fabricated by direct carbonization of Co-based metal-organic framework in nitrogen atmosphere without using any additional carbon precursors. The MNC was used as an effective magnetic adsorbent for the extraction and enrichment of some phenylurea herbicides (monuron, isoproturon, diuron and buturon) in grape and bitter gourd samples prior to their determination by high performance liquid chromatography with ultraviolet detection. Several important experimental parameters that could influence the extraction efficiency were investigated and optimized. Under the optimum conditions, a good linearity was achieved in the concentration range of 1.0–100.0 ng g−1 for monuron, diuron and buturon and 1.5–100.0 ng g−1 for isoproturon with the correlation coefficients (r) larger than 0.9964. The limits of detection (S/N = 3) of the method were in the range from 0.17 to 0.46 ng g−1. The results indicated that the MNC material was stable and efficient adsorbent for the magnetic solid-phase extraction of phenylurea herbicides and would have a great application potential for the extraction and preconcentration of more organic pollutants from real samples.
Co-reporter:Xingli Liu;Chun Wang;Zichen Wang;Qiuhua Wu
Microchimica Acta 2015 Volume 182( Issue 11-12) pp:1903-1910
Publication Date(Web):2015/08/01
DOI:10.1007/s00604-015-1530-8
We describe the preparation of nanoporous carbon using a metal-organic framework (MOF) as a template and furfuryl alcohol as the source for carbon. The MOF consists of a zeolitic framework (ZIF-8) that was obtained from 2-methylimidazole and Zn(II) ions. ZIF-8 was soaked with furfuryl alcohol which then was carbonized at 900 °C. The resulting nanoporous carbon (MOF-C) exhibits a high specific surface area and a large pore volume. It was used as a dispersive solid-phase adsorbent for the preconcentration of the benzoylurea insecticides diflubenzuron, triflumuron, hexaflumuron and teflubenzuron from water and tangerine samples. Under optimized conditions, the methods exhibits excellent extraction performance. The insecticides can be quantified via HPLC with UV detection in the 0.5 to 100 ng mL−1 concentration range in case of spiked tap water, and in the 2.0 to 200 ng g−1 concentration range in case of tangerines. The limits of detection range from 0.10 to 0.23 ng mL−1 in case of water samples, and from 0.34 to 0.71 ng g−1 for tangerine sample (at an S/N ratio of 3). Mean recoveries range from 91.7 to 107.9 %, with relative standard deviations of <7.1 %. The results indicate that the method was efficient for the preconcentration of trace levels of benzoylurea insecticides from water and tangerine samples. Conceivably, this new adsorbent has a large potential with respect to the enrichment of other organic pollutants from various kinds of samples.
Co-reporter:Lin Hao, Chun Wang, Qiuhua Wu, Zhi Li, Xiaohuan Zang, and Zhi Wang
Analytical Chemistry 2014 Volume 86(Issue 24) pp:12199
Publication Date(Web):November 20, 2014
DOI:10.1021/ac5031896
The fabrication of a magnetic nanoporous carbon (MNPC) via one-step direct carbonization of Co-based metal–organic framework has been achieved without using any additional carbon precursors. The morphology, structure, and magnetic behavior of the as-prepared Co-MNPC were characterized by using the techniques of scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Raman spectroscopy, N2 adsorption, and vibrating sample magnetometer. The Co-MNPC has a high specific surface area, large pore volume, and super paramagnetism. Its performance was evaluated by the magnetic solid-phase extraction of some neonicotinoid insecticides from water and fatmelon samples followed by high-performance liquid chromatographic analysis. The effects of the main experimental parameters that could affect the extraction efficiencies were investigated. The results demonstrated that the Co-MNPC had an excellent adsorption capability for the compounds.
Co-reporter:Xiumin Yang, Shuaihua Zhang, Juntao Wang, Chun Wang, Zhi Wang
Analytica Chimica Acta 2014 Volume 814() pp:63-68
Publication Date(Web):3 March 2014
DOI:10.1016/j.aca.2014.01.027
•Two-step stacking in CZE was developed for the on-line preconcentration of alkaloids.•The sensitivity of the method was much improved.•The study expanded the application of the stacking technique to the analysis of more complex matrix samples.An on-line sample preconcentration method by two-step stacking i.e., sweeping and micelle to solvent stacking, in capillary zone electrophoresis (CZE) has been developed for the determination of strychnine and brucine in traditional Chinese herbal medicines. After experimental optimizations, the best separation was achieved by using 75 mM phosphate buffer (pH 2.5) with 30% methanol (v/v). Compared with normal CZE injection, 51- and 38-fold improvement in concentration sensitivity was achieved for strychnine and brucine, respectively. The calibration curve was linear in the range of 0.1–5.0 μg mL−1 for both strychnine and brucine, with the correlation coefficients of 0.9998 and 0.9997, respectively. The limits of detection (S/N = 3) for both alkaloids were 0.01 μg mL−1. The inter-day (n = 8) and intra-day (n = 5) reproducibilities expressed as the relative standard deviations for corrected peak area were less than 9.5%. The method was applied to determine strychnine and brucine in two Chinese herbal medicines, with recoveries ranging from 94.2% to 105.4%. The results indicated that the method is simple, rapid, reliable, and can be applied to determine strychnos alkaloids in traditional Chinese herbal medicines.
Co-reporter:Xiaoxing Ma, Juntao Wang, Qiuhua Wu, Chun Wang, Zhi Wang
Food Chemistry 2014 Volume 157() pp:119-124
Publication Date(Web):15 August 2014
DOI:10.1016/j.foodchem.2014.02.007
•Graphene reinforced hollow fibre liquid phase microextraction for carbamates in fruits.•The method exhibited good linearity, good precision, and high sensitivity.•The method could be a good approach of choice for the analysis of the carbamates in fruits.Graphene reinforced hollow fibre liquid phase microextraction combined with high performance liquid chromatography–diode array detection was developed for the determination of some carbamate pesticides (metolcarb, carbaryl, isoprocarb, and diethofencarb) in fruit samples. The main parameters that affect the extraction efficiency for the carbamates were investigated. Under the optimum conditions, a good linearity was observed in the range of 1.0–100.0 ng g−1 for carbaryl and 3.0–100.0 ng g−1 for the other three analytes, with the correlation coefficients (r) of 0.9965–0.9993. The limits of detection of the method ranged from 0.2 to 1.0 ng g−1. The relative standard deviations were in the range from 6.2% to 7.8%. The results indicated that the developed method is sensitive and efficient for the determination of the carbamate pesticides in fruit samples.
Co-reporter:Na Xie, Xiaojing Ding, Xinyu Wang, Ping Wang, Shan Zhao, Zhi Wang
Journal of Pharmaceutical and Biomedical Analysis 2014 Volume 88() pp:509-512
Publication Date(Web):25 January 2014
DOI:10.1016/j.jpba.2013.10.003
•TGA was well separated from matrix, which was beneficial for quantitation.•Sample solution could be directly injected after simple sample pretreatment.•High sample throughput without solvents is beneficial for routine analysis.•The results of HPLC, IC and CE demonstrated the accuracy of the CE method.A new and simple method for the accurate determination of thioglycolic acid (TGA) in cosmetics was developed using capillary electrophoresis (CE) with diode array detection at 236 nm. The CE separation was performed on an uncoated fused silica capillary with a separation buffer solution containing 300 mmol L−1 tri-sodium phosphate and 0.5 mmol L−1 cetyltrimethylammonium bromide at a voltage of −5 kV. Both the intra- and inter-day precisions of the method were 1.4%. The calibration curve between the corrected peak areas and the concentrations of the TGA was linear within the concentration range of 0.006–1.0 mg mL−1 with a correlation coefficient (r) of 0.9998. The limit of detection and limit of quantitation were 0.002 mg mL−1 (S/N = 3) and 0.006 mg mL−1 (S/N = 10), respectively. The average recoveries at the spiked levels of 0.125, 0.250 and 0.500 mg mL−1 were 96.9%, 102.3% and 94.0% with the relative standard derivations of 2.1%, 3.9% and 2.2%, respectively. The method was cross-validated by both high performance liquid chromatographic and ion chromatographic method. Eighty-five commercial depilatory creams and hair-treatment products were analyzed with satisfactory results.
Co-reporter:Chen-Huan Wang, Xiao-Xing Ma, Chun Wang, Qiu-Hua Wu, Zhi Wang
Chinese Chemical Letters 2014 Volume 25(Issue 12) pp:1625-1629
Publication Date(Web):December 2014
DOI:10.1016/j.cclet.2014.06.018
Thin-film microextraction (TFME), a new geometry for solid-phase microextraction, has become an attractive sample-preparation technique. Compared to other microextraction approaches, the sensitivity of this technique was enhanced without sacrificing the sampling time due to the high surface area-to-volume ratio together with the increase of extraction-phase volume. In this paper, a new TFME method based on poly(vinylidene fluoride) membrane was developed for the extraction of benzoylurea insecticides (diflubenzuron, triflumuron, hexaflumuron and teflubenzuron) from water samples followed by their determination with high performance liquid chromatography-diode array detection. Under the optimal conditions, good linearity was observed over the concentration range of 0.5–100.0 ng/mL with correlation coefficient greater than 0.9994. The limits of detection (S/N = 3) of the method for the target analytes were 0.1 ng/mL. Mean recoveries ranged from 87.7% to 103.9% with relative standard deviations lower than 6.5%. The results indicated that the developed TFME method is simple, efficient, and cost effective.A new TFME method based on poly(vinylidene fluoride) membrane was developed for the extraction of benzoylurea insecticides (diflubenzuron, triflumuron, hexaflumuron and teflubenzuron) from water samples followed by their determination with high performance liquid chromatography-diode array detection.
Co-reporter:Meng Sun, Qiuhua Wu, Chun Wang and Zhi Wang
Analytical Methods 2014 vol. 6(Issue 16) pp:6316-6321
Publication Date(Web):12 Mar 2014
DOI:10.1039/C4AY00284A
Poly(vinylidene fluoride) (PVDF) has attracted enormous attention as a membrane material with regard to its excellent properties in recent years. In this paper, a new sample preparation technique, the PVDF membrane as the extraction phase, has been applied to the extraction of four endocrine-disrupting compounds: bisphenol A (BPA), 4-t-octylphenol (4-t-OP), nonylphenol (NP), and 4-nonylphenol (4-NP) from water samples for the first time, prior to their determination by high performance liquid chromatography-ultraviolet detection. Some important experimental parameters affecting the extraction efficiency were optimized. Good linearity was observed over the concentration range of 1.0–100.0 ng mL−1 for BPA, and 2.0–100 ng mL−1 for 4-t-OP, NP and 4-NP with the correlation coefficients (r) greater than 0.9934. The limit of detection (S/N = 3) of the method was 0.2 ng mL−1 for BPA and 0.4 ng mL−1 for 4-t-OP, NP and 4-NP. The method is convenient, cost effective and can be a useful alternative approach for the extraction and determination of the endocrine-disrupting compounds in water samples.
Co-reporter:Xiumin Yang, Shujing Liu, Shuaihua Zhang, Chun Wang and Zhi Wang
Analytical Methods 2014 vol. 6(Issue 15) pp:6066-6072
Publication Date(Web):30 May 2014
DOI:10.1039/C4AY00808A
In this research, a novel on-line two-step stacking preconcentration method by sweeping and micelle to solvent stacking in capillary zone electrophoresis was developed and validated for the simultaneous determination of quinolizidine alkaloids (sophocarpine, matrine and oxymatrine) in traditional Chinese medicines. Strychnine was used as an internal standard. The main parameters that affect the separation and sensitivity were investigated and optimized. Under the optimum conditions, the sensitivity enhancement factors obtained by the developed method for the analytes were from 42- to 52-fold. The method showed a good linearity over the range of 0.1–10.0 μg mL−1 for sophocarpine, matrine and oxymatrine with the correlation coefficients (r) varying from 0.9992 to 0.9996. The limits of detection (S/N = 3) were 0.02–0.03 μg mL−1. The intra-day (n = 8) and inter-day (n = 5) precisions of the method expressed as the relative standard deviation (RSD) were found to be less than 10%. The recoveries of the analytes by the method for the analysis of traditional Chinese medicines were in the range from 87.5% to 109.0% with RSDs (n = 3) less than 8.9%.
Co-reporter:Lin Hao, Chenhuan Wang, Xiaoxing Ma, Qiuhua Wu, Chun Wang and Zhi Wang
Analytical Methods 2014 vol. 6(Issue 15) pp:5659-5665
Publication Date(Web):15 May 2014
DOI:10.1039/C4AY00893F
In this paper, a three-dimensional graphene-based magnetic nanocomposite (3D-G-Fe3O4) was synthesized and used as an effective adsorbent for the extraction of four phthalate esters (dimethyl(o-)phthalate, diethyl(o-)phthalate, diallyo(o-)phthalate and bis(2-propylheptyl)phthalate) from fruit juice prior to high performance liquid chromatography analysis. The three-dimensional nanoporous structure of the 3D-G endows the new material with a high adsorption capacity. The properties and morphology of the 3D-G-Fe3O4 were characterized by transmission electron microscopy, scanning electron microscopy and infrared spectroscopy. Several experimental parameters affecting the extraction efficiencies, such as the amount of the 3D-G-Fe3O4, extraction time, sample pH, salt addition and desorption conditions were optimized. Under the optimum conditions, the limits of detection (S/N = 3) of the method for the analytes were between 0.04 and 0.13 ng mL−1. The recoveries of the method for the analytes were in the range from 87.0% to 97.8%. The result showed that the 3D-G-Fe3O4 has an excellent adsorption capacity for the analytes.
Co-reporter:Lu Wang, Xiaohuan Zang, Qingyun Chang, Chun Wang and Zhi Wang
Analytical Methods 2014 vol. 6(Issue 1) pp:253-260
Publication Date(Web):29 Oct 2013
DOI:10.1039/C3AY41454J
A graphene-based magnetic nanocomposite (Fe3O4@SiO2–G) was synthesized and used as the adsorbent for the extraction of fourteen pesticides in tomato and rape samples prior to their gas chromatography-mass spectrometry (GC-MS) detection. Various experimental parameters affecting the extraction efficiencies, such as the amount of Fe3O4@SiO2–G, extraction time, the pH and salt concentration of the sample solution and desorption conditions were investigated. Under optimized experimental conditions, good linearity existed in the range of 1.0–100.0 ng g−1 for all the analytes with the correlation coefficients (r) ranging from 0.9972 to 0.9996. The limits of detection (S/N = 3) of the method for the compounds were between 0.005 and 0.030 ng g−1 for the vegetable samples. Good reproducibilities were obtained with the relative standard deviations (RSDs) below 12.5% (n = 5). The recoveries of the method were in the range between 83.2% and 110.3%.
Co-reporter:Meng Sun;Ranxiao Tang;Qiuhua Wu;Chun Wang
Food Analytical Methods 2014 Volume 7( Issue 5) pp:1097-1102
Publication Date(Web):2014 May
DOI:10.1007/s12161-013-9719-0
Graphene, as a kind of novel and interesting carbon material, has gained much attention in recent years. In this paper, a new sample preparation technique, graphene reinforced hollow fiber liquid phase microextraction (G-HF-LPME), was developed and used to pre-concentrate some phenylurea herbicides (chlortoluron, isoproturon, diuron, monolinuron, and buturon) in milk sample prior to high-performance liquid chromatography–ultraviolet detection. Different parameters influencing the extraction efficiency of the G-HF-LPME were investigated and optimized. Under the optimized conditions, a good linearity was observed in the range between 10.0 and 400.0 μg L−1 with the correlation coefficients ranging from 0.9911 to 0.9987. The limit of detection (S/N = 3) of the method was lower than 2.0 μg L−1. The developed method is simple, efficient, and has been successfully applied to the determination of the phenylureas in milk samples.
Co-reporter:Xiaoxing Ma;Juntao Wang;Qiuhua Wu;Chun Wang
Food Analytical Methods 2014 Volume 7( Issue 7) pp:1381-1386
Publication Date(Web):2014 August
DOI:10.1007/s12161-013-9760-z
A new analytical method by graphene-reinforced hollow fiber liquid-phase microextraction combined with high-performance liquid chromatography fluorescence detection was developed for the determination of bisphenol A and 4-tert-butylphenol in bottled juices. Several important experimental parameters were studied to get optimal extraction conditions for the analytes. Under the optimized conditions, the method showed a good performance having a linear response in the range from 0.05 to 10.0 ng mL−1 with the correlation coefficients (r) of 0.9965–0.9994 and limits of detection of 0.01 ng mL−1. The relative standard deviations were in the range from 6.4 to 7.2 % at the spiked concentration of 1.0 ng mL−1. The method combines the high-adsorption capacity of graphene and the excellent clean-up performance of hollow fiber liquid-phase microextraction and has been successfully applied to the analysis of the analytes in bottled juice samples.
Co-reporter:Guijiang Zhang, Xiaohuan Zang, Zhi Li, Chun Wang, Zhi Wang
Talanta 2014 Volume 129() pp:600-605
Publication Date(Web):1 November 2014
DOI:10.1016/j.talanta.2014.06.013
•MOFs were coated onto a stainless steel wire via the sol–gel method.•The fibers were effective for the extraction of PAHs.•The fabricated fibers possessed good thermal stability and good reproducibility.•The fibers showed much higher extraction efficiency than commercial PDMS fiber.In this study, polydimethylsiloxane/metal-organic frameworks (PDMS/MOFs), including PDMS/MIL-101 and PDMS/MOF-199, were immobilized onto a stainless steel wire through sol–gel technique as solid-phase microextraction (SPME) fiber coating. The prepared fibers were used for the extraction of some polycyclic aromatic hydrocarbons (PAHs) from water samples prior to gas chromatography–mass spectrometry (GC–MS) analysis. Under the optimized experiment conditions, the PDMS/MIL-101 coated fiber exhibited higher extraction efficiency towards PAHs than that of PDMS/MOF-199. Several parameters affecting the extraction of PAHs by SPME with PDMS/MIL-101 fiber, including the extraction temperature, extraction time, sample volume, salt addition and desorption conditions, were investigated. The limits of detection (LODs) were less than 4.0 ng L−1 and the linearity was observed in the range from 0.01 to 2.0 µg L−1 with the correlation coefficients (r) ranging from 0.9940 to 0.9986. The recoveries of the method for the PAHs from water samples at spiking levels of 0.05 and 0.2 µg L−1 ranged from 78.2% to 110.3%. Single fiber repeatability and fiber-to-fiber reproducibility were less than 9.3% and 13.8%, respectively.
Co-reporter:Meng Sun;Xiaoxing Ma;Juntao Wang;Weina Wang;Qiuhua Wu;Chun Wang
Journal of Separation Science 2013 Volume 36( Issue 8) pp:1478-1485
Publication Date(Web):
DOI:10.1002/jssc.201201036
In this paper, a novel graphene (G) grafted silica-coated Fe3O4 nanocomposite was fabricated by the chemical bonding of G onto the surface of silica-coated Fe3O4 nanoparticles. Some carbamates (metolcarb, carbaryl, pirimicarb, and diethofencarb) in cucumber and pear samples were enriched by this nanocomposite prior to their determination by HPLC with UV detection. Experimental parameters that may affect the extraction efficiency were investigated. Under the optimum conditions, a linear response was achieved in the concentration range of 0.5–100.0 ng/g for metolcarb, carbaryl, and diethofencarb, and 1.0–100 ng/g for pirimicarb with the correlation coefficients (r) ranging from 0.9956 to 0.9984. The LOD (S/N = 3) of the method were found to be in the range from 0.08 to 0.2 ng/g. The RSDs were in the range from 2.4 to 5.8%. The results indicated that the G grafted silica-coated Fe3O4 nanocomposite was stable and efficient for magnetic SPE and has a great application potential for the preconcentration of other organic pollutants from real samples.
Co-reporter:Mengying Hou;Xiaohuan Zang;Chun Wang
Journal of Separation Science 2013 Volume 36( Issue 19) pp:3242-3248
Publication Date(Web):
DOI:10.1002/jssc.201300656
Graphene-grafted ferroferric oxide microspheres were used as the adsorbent to extract some pyrethroid pesticides (bifenthrin, λ-cyhalothrin, cyfluthrin, cypermethrin, fenvalerate, and deltamethrin) from orange and lettuce samples prior to their determination by GC–MS. The main variables that could affect the extraction, including the amount of the adsorbent, pH of the sample solution, extraction time, concentration of salt, and desorption conditions, were investigated and optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.3–100.0 ng/g for the analytes with the coefficients of determination ranging from 0.9877 to 0.9925. The LODs for the pyrethroids ranged from 0.01 to 0.02 ng/g. The method provided a good repeatability with RSDs < 10.6%. The recoveries for the six pyrethroid pesticides were in the range from 90.0 to 103.7%. The method was applied to the determination of the pesticides in orange and lettuce samples with a satisfactory result.
Co-reporter:Meng Sun, Ranxiao Tang, Qiuhua Wu, Chun Wang and Zhi Wang
Analytical Methods 2013 vol. 5(Issue 20) pp:5694-5700
Publication Date(Web):15 Aug 2013
DOI:10.1039/C3AY40966J
A novel graphene reinforced hollow fiber liquid phase microextraction method was developed for the extraction of phthalates (PAEs) from water, juice and milk samples prior to their determination by high performance liquid chromatography. The main factors that affect the extraction efficiency, such as fiber length, concentration of graphene, extraction time, the pH and ionic strength of the sample solution, and stirring rate were investigated and optimized. Under the optimum conditions, the concentration factors for the analytes ranged between 59 and 71. The limits of detection (S/N = 3) of the method were between 0.2 and 1.2 ng mL−1 for water and juice samples, and between 2.5 and 5.0 ng mL−1 for milk samples. The recoveries of the method were in the range between 81.0% and 108.0% for water, juice and milk samples. The results indicated that the method was rapid, efficient and environmental friendly for the determination of PAEs in different matrix samples.
Co-reporter:Xiaoxing Ma, Juntao Wang, Meng Sun, Weina Wang, Qiuhua Wu, Chun Wang and Zhi Wang
Analytical Methods 2013 vol. 5(Issue 11) pp:2809-2815
Publication Date(Web):25 Mar 2013
DOI:10.1039/C3AY40207J
A novel graphene grafted silica-coated Fe3O4 (Fe3O4@SiO2-G) was synthesized and used as an efficient magnetic solid-phase extraction adsorbent for the simultaneous extraction of four neonicotinoid pesticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) from pear and tomato samples followed by high performance liquid chromatography-diode array detection. After extraction, the adsorbent could be conveniently separated from the sample solution by an external magnetic field. The main experimental parameters affecting the extraction efficiency were investigated in detail. Under the optimum conditions, a rapid and effective determination of the neonicotinoid pesticides in pear and tomato samples was achieved. The limits of detection (S/N = 3) of the method for the neonicotinoids ranged from 0.08 to 0.15 ng g−1. Good linearity and reproducibility were obtained. The recoveries of the method were in the range from 93.1% to 107.4%.
Co-reporter:Sha-Sha BAI, Zhi LI, Xiao-Huan ZANG, Chun WANG, Zhi WANG
Chinese Journal of Analytical Chemistry 2013 Volume 41(Issue 8) pp:1177-1182
Publication Date(Web):August 2013
DOI:10.1016/S1872-2040(13)60672-6
A novel analytical method was developed for the extraction and determination of five chloroacetanilide herbicides (alachlor, acetochlor, metolachlor, butachlor and pretilachlor) in water and green tea samples by graphene-based magnetic solid phase extraction and dispersive liquid-liquid microextraction followed by gas chromatography-flame ionization detection (GC-FID). Some important experimental parameters that could influence the extraction efficiency were investigated. Under the optimum conditions, as high as 3399 to 4002 fold enrichment factors for the herbicides were achieved. A good linearity was obtained in the range of 0.1–50.0 μg L−1 for all the five herbicides with the correlation coefficients (r) varying from 0.9973 to 0.9993. The limits of detection ranged from 0.01 to 0.03μg L−1. The method was applied to the analysis of the chloroacetanilide herbicides in environmental water and green tea samples with a satisfactory result. The recoveries of the method for the analytes were in the range from 80.2% to 105.3%, and the relative standard deviations were between 3.8% and 5.8%.A graphene-based magnetic solid phase extraction coupled with dispersive liquid-liquid microextraction was developed to extract five chloroacetanilide herbicides from water and green tea samples followed by gas chromatography-flame ionization detection. The method has the advantages such as simplicity and high sensitivity.
Co-reporter:Weina Wang, Ruiyang Ma, Qiuhua Wu, Chun Wang, Zhi Wang
Talanta 2013 Volume 109() pp:133-140
Publication Date(Web):15 May 2013
DOI:10.1016/j.talanta.2013.02.008
In this study, a magnetic microsphere-confined graphene (Fe3O4@SiO2-G) was prepared as a novel adsorbent for the preconcentration of some phthalate esters in environmental water and soybean milk samples prior to high performance liquid chromatography analysis. The properties and morphology of the Fe3O4@SiO2-G were characterized by transmission electron microscopy and X-ray diffraction. This novel graphene-based magnetic nanocomposite showed great adsorptive ability toward the analytes. The method, which takes the advantages of both the high adsorption capacity of G and easy phase separation of the magnetic adsorbent from the sample solution, could avoid the time-consuming experimental procedures related to the traditional solid phase extraction. Various experimental parameters that could affect the extraction efficiencies, such as the amount of Fe3O4@SiO2-G, the extraction time, the pH of sample solution and the desorption conditions, were investigated. Under the optimum conditions, the limits of detection (S/N=3) of the method for the compounds were between 0.07 and 0.10 ng mL−1 in water samples, and between 0.15 and 0.30 ng mL−1 in soybean milk samples. The relative standard deviations (RSDs) varied from 2.7% to 6.1% (n=5). The recoveries of the method were in the range between 87.2% and 109.0% for environmental water and soybean milk samples. The method is suitable to determine the five phthalate esters (diallyl phthalate, di-n-propyl-phthalate, benzyl butyl phthalate, dicyclohexyl-phthalate and diethyl-hexyl-phthalate) in environmental water and soybean milk samples.Highlights► A magnetic microsphere-confined graphene, Fe3O4@SiO2-G, was fabricated by the chemical bonding method for the first time. ► Fe3O4@SiO2-G was used as an adsorbent for the preconcentration of some phthalate esters in water and soybean milk samples. ► The sorbent was stable enough and could be a promising adsorbent for MSPE.
Co-reporter:Shuaihua Zhang, Xiumin Yang, Xiaofang Yin, Chun Wang, Zhi Wang
Food Chemistry 2012 Volume 133(Issue 2) pp:544-550
Publication Date(Web):15 July 2012
DOI:10.1016/j.foodchem.2012.01.028
A rapid, simple and sensitive method has been developed for the analysis of some neonicotinoid insecticides in cucumber samples by using dispersive liquid–liquid microextraction (DLLME) coupled with sweeping in micellar electrokinetic chromatography (MEKC). Under optimised conditions, the enrichment factors were achieved in the range from 4000 to 10,000. The linearity of the method was in the range from 2.7 to 200 ng g−1 for thiacloprid, acetamiprid and imidacloprid, and in the range from 4.0 to 200 ng g−1 for imidaclothiz in cucumber samples, with the determination coefficients (r2) ranging from 0.9924 to 0.9968. The limits of detection (LODs, S/N = 3) ranged from 0.8 to 1.2 ng g−1. The relative standard deviations (RSDs) at the concentration levels of 10.0 and 50.0 ng g−1 each of the neonicotinoid insecticides in cucumber samples varied from 3.8% to 6.3%. The developed method has been successfully applied to the analysis of the neonicotinoid insecticides in cucumbers with a satisfactory result.Highlights► Combined use of dispersive liquid–liquid microextraction with sweeping micellar electrokinetic chromatography. ► Enrichment factors of as high as 4000–10,000-fold. ► Good recoveries and reproducibilities with a short analysis time.
Co-reporter:Weina Wang;Xiaoxing Ma;Qiuhua Wu;Chun Wang;Xiaohuan Zang
Journal of Separation Science 2012 Volume 35( Issue 17) pp:2266-2272
Publication Date(Web):
DOI:10.1002/jssc.201200285
A graphene-based magnetic nanocomposite (graphene-ferriferrous oxide; G-Fe3O4) was synthesized and used as an effective adsorbent for the preconcentration of some triazole fungicides (myclobutanil, tebuconazole, and hexaconazole) in environmental water samples prior to high-performance liquid chromatography-ultraviolet detection. The method, which takes the advantages of both nanoparticle adsorption and magnetic phase separation from the sample solution, could avoid the time-consuming experimental procedures commonly involved in the traditional solid phase extraction such as centrifugation and filtrations. Various experimental parameters affecting the extraction efficiencies such as the amount of the magnetic nanocomposite, extraction time, the pH values of the sample solution, salt concentration, and desorption conditions were investigated. Under the optimum conditions, the enrichment factors of the method for the three analytes were 5824, 3600, and 4761, respectively. A good linearity was observed in the range of 0.1–50 ng/mL for tebuconazole and 0.05–50 ng/mL for myclobutanil and hexaconazole, respectively, with the correlation coefficients ranging from 0.9992 to 0.9996. The limits of detection (S/N = 3) of the method were between 0.005 and 0.01 ng/mL. The results indicated that as a magnetic solid-phase extraction adsorbent, the graphene-ferriferrous oxide (G-Fe3O4) has a great potential for the preconcentration of some compounds from liquid samples.
Co-reporter:Weina Wang, Yunpeng Li, Qiuhua Wu, Chun Wang, Xiaohuan Zang and Zhi Wang
Analytical Methods 2012 vol. 4(Issue 3) pp:766-772
Publication Date(Web):23 Feb 2012
DOI:10.1039/C2AY05734D
In this paper, a kind of graphene magnetic nanoparticle (G–Fe3O4) was prepared and used as the adsorbent for the preconcentration of the four neonicotinoid insecticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) from environmental water samples. The properties of the magnetic adsorbent were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. After preconcentration, the adsorbent can be conveniently separated from the aqueous samples by an external magnet, and the analytes desorbed were determined by high performance liquid chromatography-ultraviolet detection (HPLC-UV). Various parameters affecting the extraction efficiencies such as the concentration of G–Fe3O4, the extraction time, the pH of the sample solution, the salinity and the desorption conditions were investigated. Under the optimum conditions, the concentration factors for the analytes ranged between 3325 and 4644. The linearity of the method was in the range from 0.05 to 50 ng mL−1 with the correlation coefficients (r) ranging from 0.9990 to 0.9995. The limits of detection (S/N = 3) of the method for thiamethoxam, imidacloprid, acetamiprid and thiacloprid were 0.01, 0.006, 0.004 and 0.006 ng ml−1, respectively. The relative standard deviations (RSDs) varied from 4.3% to 7.4% (n = 6), and the recoveries of the method for the compounds at spiking levels of 0.5 and 5 ng mL−1 were in the range of 86%–110%. The method has been successfully applied to the analysis of the neonicotinoid insecticides in real water samples.
Co-reporter:Shuaihua Zhang, Ruiyang Ma, Xiumin Yang, Chun Wang, Zhi Wang
Journal of Chromatography B 2012 Volume 906() pp:41-47
Publication Date(Web):1 October 2012
DOI:10.1016/j.jchromb.2012.08.017
A sensitive method for the determination of three cationic alkaloids (berberine, palmatine and jatrorrhizine) from human plasma samples was developed by micelle to solvent stacking (MSS) in capillary zone electrophoresis (CZE). In MSS, the sample preconcentration mainly relies on the reversal in the effective electrophoretic mobility of the analytes at the boundary zone between the sample and CZE background solution (BGS). Under the optimized conditions, the sensitivity enhancement factors achieved in terms of corrected peak area were in the range from 47 to 53 for the alkaloids. The limits of detection (LODs) (S/N = 3) for berberine, palmatine and jatrorrhizine were 0.01, 0.01 and 0.02 μg/mL, respectively. The intraday (n = 6) and interday repeatabilities (n = 12) expressed as the relative standard deviations (RSDs) were less than 6.9% in terms of peak height and less than 7.3% in terms of corrected peak area, respectively. The recoveries of the method for the three alkaloids were in the range of 95.9–101.5% with peak height as the quantitative signal, and 92.6–103.6% with corrected peak area as the quantitative signal, respectively. The MSS-CZE method proved to be suitable for the analysis of the alkaloids in human plasma samples.Highlights► On-line sample concentration and analysis of some cationic alkaloids in human plasma. ► Micelle to solvent stacking in capillary zone electrophoresis. ► High sensitivity and good recovery.
Co-reporter:Chun Xia Wu, Qiu Hua Wu, Chun Wang, Zhi Wang
Chinese Chemical Letters 2011 Volume 22(Issue 4) pp:473-476
Publication Date(Web):April 2011
DOI:10.1016/j.cclet.2010.10.049
A novel, simple, rapid, efficient and environment-friendly method for the determination of trace copper in cereal samples was developed by using dispersive liquid–liquid microextraction based on solidification of floating organic drop (DLLME-SFO) followed by flame atomic absorption spectrometry. In the DLLME-SFO, copper was complexed with 8-hydroxy quinoline and extracted into a small volume of 1-dodecanol, which is of low density, low toxicity and proper melting point near room temperature. The experimental parameters affecting the extraction efficiency were investigated and optimized. Under the optimum conditions, the calibration graph exhibited linearity over the range of 0.5–500 ng/mL with the correlation coefficient (r) of 0.9996. The enrichment factor was 122 and the limit of detection was 0.1 ng/mL. The method was applied to the determination of copper in the complex matrix samples such as rice and millet with the recoveries for the spiked samples at 5.0 and 10.0 μg/g falling in the range of 92.0–98.0% and the relative standard deviation of 3.9–5.7%.
Co-reporter:Xiao Fang Yin, Zhi Li, Shuai Hua Zhang, Chun Xia Wu, Chun Wang, Zhi Wang
Chinese Chemical Letters 2011 Volume 22(Issue 3) pp:330-333
Publication Date(Web):March 2011
DOI:10.1016/j.cclet.2010.10.044
A novel micelle to solvent stacking on-line sample preconcentration technique in capillary zone electrophoresis (MSS-CZE) has been developed to determine the strychnine and brucine in traditional Chinese medicine preparations. The optimal running buffer was 30 mmol/L H3PO4 containing 20% acetonitrile at pH 4.0. The sample matrix was 8 mmol/L H3PO4 containing 5 mmol/L sodium dodecyl sulfate (SDS) at pH 3.0. The established MSS-CZE method afforded more than 50-fold improvements in concentration sensitivity compared with typical CZE-UV analysis. The calibration curve was linear in the range from 0.2 to 15.0 μg/mL for both strychnine and brucine, with correlation coefficients of 0.9984 and 0.9976, respectively. The limits of detection (S/N = 3:1) for strychnine and brucine were 0.02 and 0.05 μg/mL, respectively. The MSS-CZE method has been successfully applied to the analysis of strychnine and brucine in Chinese medicinal preparations.
Co-reporter:Guangying Zhao, Shuangju Song, Chun Wang, Qiuhua Wu and Zhi Wang
Analytical Methods 2011 vol. 3(Issue 12) pp:2929-2935
Publication Date(Web):08 Nov 2011
DOI:10.1039/C1AY05358B
In this study, a novel graphene nanocomposite was synthesized and used as a solid-phase microextraction fiber coating material. The application of the graphene-coated fiber was evaluated through the extraction and determination of the four carbamate pesticides (carbofuran, carbaryl, pirimicarb, diethofencarb) in water samples by high performance liquid chromatography-diode array detection. Parameters that affect the extraction efficiencies, such as the extraction time, stirring rate, extraction temperature, and salt addition, were investigated and optimized. Compared with the two commonly used commercial fibers (CW/TPR, 50 μm; PDMS/DVB, 60 μm), the graphene-coated fiber showed higher extraction efficiency. Under the optimum conditions, the limits of detection (LODs), based on a signal-to-noise ratio (S/N) of 3, were 0.1–0.8 ng mL−1. The limits of quantification (LOQ, S/N = 9) were 0.3–2.4 ng mL−1. The linearity was observed in the range from their corresponding LOQs to 400.0 ng mL−1 with the correlation coefficients (r) ranging from 0.9994 to 0.9998. The recoveries of the carbamate pesticides from water samples at spiking levels of 10.0, 50.0 and 100 ng mL−1 were in the range of 83.8%–95.4%, and the relative standard deviations were between 2.2% and 6.6%.
Co-reporter:Xiaojing Ding;Yuanyuan Yang;Shan Zhao;Yun Li
Dairy Science & Technology 2011 Volume 91( Issue 2) pp:213-225
Publication Date(Web):2011 April
DOI:10.1007/s13594-011-0006-9
Two analytical methods, capillary electrophoresis (CE) with UV detection and high-performance liquid chromatography (HPLC) with photodiode array detection, were developed for the determination of α-lactalbumin (α-Lac), β-lactoglobulin A (β-Lg A), and β-lactoglobulin B (β-Lg B) in whey protein powder, colostrum, raw milk, and infant formula. The CE analysis was performed in a bare fused silica capillary (57 cm × 50 μm, effective length 50 cm) with a separation buffer consisting of 0.5 mol L−1 boric acid, 0.025 mol L−1 hydroxypropyl-β-cyclodextrin, and 0.8 g L−1 poly(ethylene oxide) 4,000,000 at pH 9.10. The HPLC analysis was performed on a CAPCELL PAK C8 SG 300 (200 × 4.6 mm, 5-μm particles) column with a gradient mobile phase mixture consisting of acetonitrile and water containing trifluoroacetic acid. The CE method is suitable for the simultaneous determination of α-Lac, β-Lg A, and β-Lg B in whey powder, colostrum, and raw bovine milk, whereas the HPLC method can only be used for quantitative assays of β-Lg A and β-Lg B due to the co-elution of lactoferrin with α-Lac. Recoveries for both methods over the concentration range were between 90.7% and 116.8%. Whey protein powder had the highest content of the above three proteins. The contents of α-Lac in infant formula increased with the raise of age stage. Infant formula with the same age stage but different brands and countries had significant differences in the content of α-Lac.本文建立了紫外检测-毛细管电泳 (CE-UV) 及二极管阵列检测-高效液相色谱 (HPLC) 测定乳清蛋白粉、初乳、原料奶及婴儿配方奶粉中α-乳白蛋白 (α-Lac) 、β-乳球蛋白A (β-Lg A) 及β-乳球蛋白B (β-Lg B) 的新方法。CE法以石英毛细管柱 (57 cm × 50 μm, 有效长度50 cm) 为分离柱、以0.5 mol L−1硼酸、0.025 mol L−1羟丙基β-环糊精及0.8 g L−1 聚乙烯醇4,000,000为分离缓冲液 (pH 9.10)。HPLC法以CAPCELL PAK C8 SG 300 (200 × 4.6 mm, 5 μm)为色谱分离柱, 以含乙腈及三氟乙酸的流动相梯度淋洗方式实现了上述三个蛋白的分离与测定。CE方法适合于乳清蛋白粉、牛初乳及原料奶样品中α-Lac、β-Lg A 及, β-Lg B的同时分离与测定, 而HPLC法中因乳铁蛋白干扰α-Lac, 仅能定量其中的β-Lg A 及 β-Lg B。两种方法在测定的浓度范围内回收率在90.7–116.8%间。乳清蛋白粉中上述三个蛋白的含量最高, 婴儿配方奶粉中α-Lac含量随着年龄阶段数的增加而增加, 而且同一阶段内不同厂家不同国别婴儿配方奶粉中α-Lac含量差异也较大。
Co-reporter:Shuaihua Zhang, Chao Li, Shuangju Song, Tao Feng, Chun Wang and Zhi Wang
Analytical Methods 2010 vol. 2(Issue 1) pp:54-62
Publication Date(Web):23 Nov 2009
DOI:10.1039/B9AY00115H
A rapid and sensitive method for the multiresidue analysis of six commonly used carbamate pesticides in apples was developed by using dispersive liquid–liquid microextraction (DLLME) coupled with sweeping micellar electrokinetic chromatography (MEKC). Parameters that affect the extraction and sweeping efficiency, such as the kind and volume of the extraction and disperser solvent, extraction time, salt addition, sample matrix and concentration of organic modifiers in the separation buffer were investigated and optimized. Under optimized conditions, the enrichment factors were achieved in the range from 491 to 1834. The linearity of the method for methiocarb, diethofencarb, carbaryl and isoprocarb was in the range of 6–500 ng g−1, and for fenobcarb and tsumacide in the range of 9–500 ng g−1, with the correlation coefficients (r) ranging from 0.9952 to 0.9990. The limits of detection (LODs) at a signal-to-noise ratio of 3 ranged from 2.0 to 3.0 ng g−1. The recoveries of the six carbamates for apple samples at spiking levels of 20.0 and 100.0 ng g−1 were 85.5–108.1% and 85.4–113.3%, respectively. The proposed method has been successfully applied to the analysis of the target carbamate residues in apple samples with satisfactory results.
Co-reporter:Qiuhua Wu, Yunpeng Li, Chun Wang, Zhimei Liu, Xiaohuan Zang, Xin Zhou, Zhi Wang
Analytica Chimica Acta 2009 Volume 638(Issue 2) pp:139-145
Publication Date(Web):13 April 2009
DOI:10.1016/j.aca.2009.02.017
A rapid and sensitive method for the determination of carbendazim (methyl benzimidazole-2-ylcarbamate, MBC) and thiabendazole (TBZ) in water and soil samples was developed by using dispersive liquid–liquid microextraction (DLLME) coupled with high performance liquid chromatography with fluorescence detection. The water samples were directly used for the DLLME extraction. For soil samples, the target analytes were first extracted by 0.1 mol L−1 HCl. Then, the pH of the extract was adjusted to 7.0 with 2 mol L−1 NaOH before the DLLME extraction. In the DLLME extraction method, chloroform (CHCl3) was used as extraction solvent and tetrahydrofuran (THF) as dispersive solvent. Under the optimum conditions, the enrichment factors for MBC and TBZ were ranged between 149 and 210, and the extraction recoveries were between 50.8 and 70.9%, respectively. The linearity of the method was obtained in the range of 5–800 ng mL−1 for water sample analysis, and 10–1000 ng g−1 for soil samples, respectively. The correlation coefficients (r) ranged from 0.9987 to 0.9997. The limits of detection were 0.5–1.0 ng mL−1 for water samples, and 1.0–1.6 ng g−1 for soil samples. The relative standard deviations (RSDs) varied from 3.5 to 6.8% (n = 5). The recoveries of the method for MBC and TBZ from water samples at spiking levels of 5 and 20 ng mL−1 were 84.0–94.0% and 86.0–92.5%, respectively. The recoveries for soil samples at spiking levels of 10 and 100 ng g−1 varied between 82.0 and 93.4%.
Co-reporter:Qiuhua Wu, Chun Wang, Zhimei Liu, Chunxia Wu, Xin Zeng, Jialin Wen, Zhi Wang
Journal of Chromatography A 2009 Volume 1216(Issue 29) pp:5504-5510
Publication Date(Web):17 July 2009
DOI:10.1016/j.chroma.2009.05.062
Dispersive solid-phase extraction (DSPE) combined with dispersive liquid–liquid microextraction (DLLME) has been developed as a new approach for the extraction of four sulfonylurea herbicides (metsulfuron-methyl, chlorsulfuron, bensulfuron-methyl and chlorimuron-ethyl) in soil prior to high-performance liquid chromatography with diode array detection (HPLC-DAD). In the DSPE-DLLME, sulfonylurea herbicides were first extracted from soil sample into acetone–0.15 mol L−1 NaHCO3 (2:8, v/v). The clean-up of the extract by DSPE was carried out by directly adding C18 sorbent into the extract solution, followed by shaking and filtration. After the pH of the filtrate was adjusted to 2.0 with 2 mol L−1 HCl, 60.0 μL chlorobenzene (as extraction solvent) was added into 5.0 mL of it for DLLME procedure (the acetone contained in the solution also acted as dispersive solvent). Under the optimum conditions, the enrichment factors for the compounds were in the range between 102 and 216. The linearity of the method was in the range from 5.0 to 200 ng g−1 with the correlation coefficients (r) ranging from 0.9967 to 0.9987. The method detection limits were 0.5–1.2 ng g−1. The relative standard deviations varied from 5.2% to 7.2% (n = 5). The relative recoveries of the four sulfonylurea herbicides from soil samples at spiking levels of 6.0, 20.0 and 60.0 ng g−1 were in the range between 76.3% and 92.5%. The proposed method has been successfully applied to the analysis of the four target sulfonylurea herbicides in soil samples, and a satisfactory result was obtained.
Co-reporter:Zhi Mei Liu, Xiao Huan Zang, Wei Hua Liu, Chun Wang, Zhi Wang
Chinese Chemical Letters 2009 Volume 20(Issue 2) pp:213-216
Publication Date(Web):February 2009
DOI:10.1016/j.cclet.2008.10.047
A novel method for the determination of five carbamate pesticides (metolcarb, carbofuran, carbaryl, isoprocard and diethofencard) in water samples was developed by dispersive liquid–liquid microextraction (DLLME) coupled with high performance liquid chromatography-diode array detector (HPLC-DAD). Some experimental parameters that influence the extraction efficiency were studied and optimized to obtain the best extraction results. Under the optimum conditions for the method, the calibration curve was linear in the concentration range from 5 to 1000 ng mL−1 for all the five carbamate pesticides, with the correlation coefficients (r2) varying from 0.9984 to 0.9994. Good enrichment factors were achieved ranging from 80 to 177-fold, depending on the compound. The limits of detection (LODs) (S/N = 3) were ranged from 0.1 to 0.5 ng mL−1. The method has been successfully applied to the analysis of the pesticide residues in environmental water samples.
Co-reporter:Xiao-Huan ZANG, Qiu-Hua WU, Mei-Yue ZHANG, Guo-Hong XI, Zhi WANG
Chinese Journal of Analytical Chemistry 2009 Volume 37(Issue 2) pp:161-168
Publication Date(Web):February 2009
DOI:10.1016/S1872-2040(08)60082-1
Dispersive liquid-liquid microextraction (DLLME) is a novel environmentally benign sample-preparation technique, possessing obvious advantages of simple operation with a high enrichment factor, low cost, and low consumption of organic solvent. Compared with those of single drop microextraction (SDME) and hollow fiber-based liquid-phase microextraction (HF-LPME), the extraction time of DLLME is greatly shortened. DLLME coupled with gas chromatography (GC), high performance liquid chromatography (HPLC), and atomic absorption spectrometry (AAS) have been widely applied to the analyses of environmental and food samples. The basic principles, parameters affecting the extraction efficiency, and the latest applications of DLLME are reviewed in the article.
Co-reporter:Chun Wang, Cairui Li, Xiaohuan Zang, Dandan Han, Zhimei Liu, Zhi Wang
Journal of Chromatography A 2007 Volume 1143(1–2) pp:270-275
Publication Date(Web):2 March 2007
DOI:10.1016/j.chroma.2007.01.027
A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextraction (LPME) based on porous polypropylene hollow fibers combined with on-line sweeping in micellar electrokinetic chromatography (MEKC) was developed. Strychnos alkaloids were first extracted from urine sample which was adjusted to alkaline conditions (0.5 mol l−1 NaOH). The unionized analytes were subsequently extracted into 1-octanol impregnated in the pores of hollow fibers, and then into an acidic acceptor solution (100 mmol l−1 H3PO4) inside the hollow fiber. The extract was analyzed directly by on-line sweeping in MEKC. In the method, the compound berberine was used as the internal standard (I.S.) for the improvement of the experimental reproducibility. The calibration curve was linear over a range of 20–200 ng ml−1 for both strychnine and brucine in human urine sample, with a correlation coefficient of 0.996 and 0.997, respectively. The detection limits (S/N = 3:1) for strychnine and brucine were 1 and 2 ng ml−1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine sample, indicating that LPME-sweeping-MEKC is a promising combination for analysis of basic drugs present at low levels in some biological matrices.
Co-reporter:Xiao Huan Zang, Cai Rui Li, Qiu Hua Wu, Chun Wang, Dan Dan Han, Zhi Wang
Chinese Chemical Letters 2007 Volume 18(Issue 3) pp:316-318
Publication Date(Web):March 2007
DOI:10.1016/j.cclet.2007.01.032
A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextraction (LPME) based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinetic chromatography was developed. The calibration curve was linear over the range of 20–200 ng mL−1 for both strychnine and brucine in human urine sample. The detection limits (S/N = 3:1) for strychnine and brucine were 1 ng mL−1 and 2 ng mL−1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.
Co-reporter:Weiqian Liang, Juntao Wang, Xiaohuan Zang, Wenhuan Dong, Chun Wang, Zhi Wang
Journal of Chromatography A (31 March 2017) Volume 1491() pp:9-15
Publication Date(Web):31 March 2017
DOI:10.1016/j.chroma.2017.02.034
Co-reporter:
Analytical Methods (2009-Present) 2015 - vol. 7(Issue 20) pp:NaN8800-8800
Publication Date(Web):2015/09/01
DOI:10.1039/C5AY01578B
Graphene grafted magnetic microspheres were prepared and used as the adsorbent for magnetic solid phase extraction (MSPE) of bisphenol A and triclosan from water samples prior to their determination by gas chromatography-mass spectrometric (GC-MS) detection. A new customized ground-glass stoppered conical flask with a side tube was used for MSPE operations to simplify the separation of the magnetic adsorbent from the sample solution. The main experimental factors affecting the extraction recoveries of the analytes including the amount of adsorbent, pH of the sample solution, extraction time, salt concentration, desorption conditions, and derivatization conditions were investigated. Under the optimal conditions, a linear response was observed in the concentration range of 0.05–2.50 μg L−1 for bisphenol A and 0.10–5.00 μg L−1 for triclosan. The limits of detection (S/N = 3) were 10.0 ng L−1 for bisphenol A and 20.0 ng L−1 for triclosan. The established method was applied to the determination of bisphenol A and triclosan residues in environmental water samples with satisfactory results. The recoveries of the analytes using this method from lake, river, bottled and tap water samples were in the range from 93.9% to 104.3% (intra-day), and from 93.5% to 99.5% (inter-day) with the relative standard deviations varying from 2.1% to 5.8% (intra-day), and from 3.1% to 5.7% (inter-day).
Co-reporter:Guangying Zhao, Shuangju Song, Chun Wang, Qiuhua Wu and Zhi Wang
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 12) pp:NaN2935-2935
Publication Date(Web):2011/11/08
DOI:10.1039/C1AY05358B
In this study, a novel graphene nanocomposite was synthesized and used as a solid-phase microextraction fiber coating material. The application of the graphene-coated fiber was evaluated through the extraction and determination of the four carbamate pesticides (carbofuran, carbaryl, pirimicarb, diethofencarb) in water samples by high performance liquid chromatography-diode array detection. Parameters that affect the extraction efficiencies, such as the extraction time, stirring rate, extraction temperature, and salt addition, were investigated and optimized. Compared with the two commonly used commercial fibers (CW/TPR, 50 μm; PDMS/DVB, 60 μm), the graphene-coated fiber showed higher extraction efficiency. Under the optimum conditions, the limits of detection (LODs), based on a signal-to-noise ratio (S/N) of 3, were 0.1–0.8 ng mL−1. The limits of quantification (LOQ, S/N = 9) were 0.3–2.4 ng mL−1. The linearity was observed in the range from their corresponding LOQs to 400.0 ng mL−1 with the correlation coefficients (r) ranging from 0.9994 to 0.9998. The recoveries of the carbamate pesticides from water samples at spiking levels of 10.0, 50.0 and 100 ng mL−1 were in the range of 83.8%–95.4%, and the relative standard deviations were between 2.2% and 6.6%.
Co-reporter:Shuaihua Zhang, Chao Li, Shuangju Song, Tao Feng, Chun Wang and Zhi Wang
Analytical Methods (2009-Present) 2010 - vol. 2(Issue 1) pp:NaN62-62
Publication Date(Web):2009/11/23
DOI:10.1039/B9AY00115H
A rapid and sensitive method for the multiresidue analysis of six commonly used carbamate pesticides in apples was developed by using dispersive liquid–liquid microextraction (DLLME) coupled with sweeping micellar electrokinetic chromatography (MEKC). Parameters that affect the extraction and sweeping efficiency, such as the kind and volume of the extraction and disperser solvent, extraction time, salt addition, sample matrix and concentration of organic modifiers in the separation buffer were investigated and optimized. Under optimized conditions, the enrichment factors were achieved in the range from 491 to 1834. The linearity of the method for methiocarb, diethofencarb, carbaryl and isoprocarb was in the range of 6–500 ng g−1, and for fenobcarb and tsumacide in the range of 9–500 ng g−1, with the correlation coefficients (r) ranging from 0.9952 to 0.9990. The limits of detection (LODs) at a signal-to-noise ratio of 3 ranged from 2.0 to 3.0 ng g−1. The recoveries of the six carbamates for apple samples at spiking levels of 20.0 and 100.0 ng g−1 were 85.5–108.1% and 85.4–113.3%, respectively. The proposed method has been successfully applied to the analysis of the target carbamate residues in apple samples with satisfactory results.
Co-reporter:Weina Wang, Yunpeng Li, Qiuhua Wu, Chun Wang, Xiaohuan Zang and Zhi Wang
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 3) pp:
Publication Date(Web):
DOI:10.1039/C2AY05734D
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 11) pp:NaN2815-2815
Publication Date(Web):2013/03/25
DOI:10.1039/C3AY40207J
A novel graphene grafted silica-coated Fe3O4 (Fe3O4@SiO2-G) was synthesized and used as an efficient magnetic solid-phase extraction adsorbent for the simultaneous extraction of four neonicotinoid pesticides (thiamethoxam, imidacloprid, acetamiprid and thiacloprid) from pear and tomato samples followed by high performance liquid chromatography-diode array detection. After extraction, the adsorbent could be conveniently separated from the sample solution by an external magnetic field. The main experimental parameters affecting the extraction efficiency were investigated in detail. Under the optimum conditions, a rapid and effective determination of the neonicotinoid pesticides in pear and tomato samples was achieved. The limits of detection (S/N = 3) of the method for the neonicotinoids ranged from 0.08 to 0.15 ng g−1. Good linearity and reproducibility were obtained. The recoveries of the method were in the range from 93.1% to 107.4%.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 20) pp:
Publication Date(Web):
DOI:10.1039/C3AY40966J
A novel graphene reinforced hollow fiber liquid phase microextraction method was developed for the extraction of phthalates (PAEs) from water, juice and milk samples prior to their determination by high performance liquid chromatography. The main factors that affect the extraction efficiency, such as fiber length, concentration of graphene, extraction time, the pH and ionic strength of the sample solution, and stirring rate were investigated and optimized. Under the optimum conditions, the concentration factors for the analytes ranged between 59 and 71. The limits of detection (S/N = 3) of the method were between 0.2 and 1.2 ng mL−1 for water and juice samples, and between 2.5 and 5.0 ng mL−1 for milk samples. The recoveries of the method were in the range between 81.0% and 108.0% for water, juice and milk samples. The results indicated that the method was rapid, efficient and environmental friendly for the determination of PAEs in different matrix samples.
Co-reporter:
Analytical Methods (2009-Present) 2015 - vol. 7(Issue 19) pp:NaN8171-8171
Publication Date(Web):2015/08/07
DOI:10.1039/C5AY01585E
In this study, an ordered mesoporous carbon (OMC) with a large surface area, uniform mesoporous structure and large pore volume was synthesized by using Zeolite Socony Mobil-5 (ZSM-5) as the hard template and sucrose as the carbon precursor. The synthesized OMC-ZSM-5 was immobilized onto a stainless steel wire for the preparation of SPME fibers by a sol–gel coating method. The SPME of polycyclic aromatic hydrocarbons (PAHs) with the OMC-ZSM-5 coated fiber coupled with gas chromatography/flame ionization detection (GC/FID) provided large enhancement factors (738–2359), low limits of detection (LODs, 0.5–1.6 ng g−1) and good linearities (1.7–100.0 ng g−1) for soil samples. The relative standard deviations (RSDs) for single fiber and fiber-to-fiber reproducibilities were in the range of 4.6–7.9% and 6.1–10.2%, respectively. The developed method was successfully applied to the analysis of soil samples and the recoveries of the analytes for the method were in the range from 88.0% to 103.8%. The OMC-ZSM-5 coated fiber was stable enough for 160 extractions without a significant loss of extraction efficiency.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 16) pp:
Publication Date(Web):
DOI:10.1039/C4AY00284A
Poly(vinylidene fluoride) (PVDF) has attracted enormous attention as a membrane material with regard to its excellent properties in recent years. In this paper, a new sample preparation technique, the PVDF membrane as the extraction phase, has been applied to the extraction of four endocrine-disrupting compounds: bisphenol A (BPA), 4-t-octylphenol (4-t-OP), nonylphenol (NP), and 4-nonylphenol (4-NP) from water samples for the first time, prior to their determination by high performance liquid chromatography-ultraviolet detection. Some important experimental parameters affecting the extraction efficiency were optimized. Good linearity was observed over the concentration range of 1.0–100.0 ng mL−1 for BPA, and 2.0–100 ng mL−1 for 4-t-OP, NP and 4-NP with the correlation coefficients (r) greater than 0.9934. The limit of detection (S/N = 3) of the method was 0.2 ng mL−1 for BPA and 0.4 ng mL−1 for 4-t-OP, NP and 4-NP. The method is convenient, cost effective and can be a useful alternative approach for the extraction and determination of the endocrine-disrupting compounds in water samples.
Co-reporter:Xiumin Yang;Shujing Liu;Shuaihua Zhang;Chun Wang
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 15) pp:
Publication Date(Web):2014/07/10
DOI:10.1039/C4AY00808A
In this research, a novel on-line two-step stacking preconcentration method by sweeping and micelle to solvent stacking in capillary zone electrophoresis was developed and validated for the simultaneous determination of quinolizidine alkaloids (sophocarpine, matrine and oxymatrine) in traditional Chinese medicines. Strychnine was used as an internal standard. The main parameters that affect the separation and sensitivity were investigated and optimized. Under the optimum conditions, the sensitivity enhancement factors obtained by the developed method for the analytes were from 42- to 52-fold. The method showed a good linearity over the range of 0.1–10.0 μg mL−1 for sophocarpine, matrine and oxymatrine with the correlation coefficients (r) varying from 0.9992 to 0.9996. The limits of detection (S/N = 3) were 0.02–0.03 μg mL−1. The intra-day (n = 8) and inter-day (n = 5) precisions of the method expressed as the relative standard deviation (RSD) were found to be less than 10%. The recoveries of the analytes by the method for the analysis of traditional Chinese medicines were in the range from 87.5% to 109.0% with RSDs (n = 3) less than 8.9%.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 15) pp:
Publication Date(Web):
DOI:10.1039/C4AY00893F
In this paper, a three-dimensional graphene-based magnetic nanocomposite (3D-G-Fe3O4) was synthesized and used as an effective adsorbent for the extraction of four phthalate esters (dimethyl(o-)phthalate, diethyl(o-)phthalate, diallyo(o-)phthalate and bis(2-propylheptyl)phthalate) from fruit juice prior to high performance liquid chromatography analysis. The three-dimensional nanoporous structure of the 3D-G endows the new material with a high adsorption capacity. The properties and morphology of the 3D-G-Fe3O4 were characterized by transmission electron microscopy, scanning electron microscopy and infrared spectroscopy. Several experimental parameters affecting the extraction efficiencies, such as the amount of the 3D-G-Fe3O4, extraction time, sample pH, salt addition and desorption conditions were optimized. Under the optimum conditions, the limits of detection (S/N = 3) of the method for the analytes were between 0.04 and 0.13 ng mL−1. The recoveries of the method for the analytes were in the range from 87.0% to 97.8%. The result showed that the 3D-G-Fe3O4 has an excellent adsorption capacity for the analytes.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 1) pp:NaN260-260
Publication Date(Web):2013/10/29
DOI:10.1039/C3AY41454J
A graphene-based magnetic nanocomposite (Fe3O4@SiO2–G) was synthesized and used as the adsorbent for the extraction of fourteen pesticides in tomato and rape samples prior to their gas chromatography-mass spectrometry (GC-MS) detection. Various experimental parameters affecting the extraction efficiencies, such as the amount of Fe3O4@SiO2–G, extraction time, the pH and salt concentration of the sample solution and desorption conditions were investigated. Under optimized experimental conditions, good linearity existed in the range of 1.0–100.0 ng g−1 for all the analytes with the correlation coefficients (r) ranging from 0.9972 to 0.9996. The limits of detection (S/N = 3) of the method for the compounds were between 0.005 and 0.030 ng g−1 for the vegetable samples. Good reproducibilities were obtained with the relative standard deviations (RSDs) below 12.5% (n = 5). The recoveries of the method were in the range between 83.2% and 110.3%.
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![cyano(3-phenoxyphenyl)methyl (1S,3S)-3-[(1Z)-2-chloro-3,3,3-trifluoroprop-1-en-1-yl]-2,2-dimethylcyclopropanecarboxylate](http://img.cochemist.com/ccimg/68100/68085-85-8.png)
![cyano(3-phenoxyphenyl)methyl (1S,3S)-3-[(1Z)-2-chloro-3,3,3-trifluoroprop-1-en-1-yl]-2,2-dimethylcyclopropanecarboxylate](http://img.cochemist.com/ccimg/68100/68085-85-8_b.png)
