Co-reporter:Yang Xu;Qi Zhao;Liyan Jiang;Zhengqiang Li
Environmental Science and Pollution Research 2017 Volume 24( Issue 10) pp:9174-9186
Publication Date(Web):18 February 2017
DOI:10.1007/s11356-017-8581-9
In the study, a simple and selective method based on magnetic separation technology is presented for the extraction of sulfonamides (SAs) from environmental water, followed by liquid chromatography–tandem mass spectrometry. In this method, magnetic surface molecularly imprinted polymers (Fe3O4@SiO2@MIPs) with super-paramagnetic property and high selectivity toward SAs were developed as magnetic adsorbents. The Fe3O4@SiO2@MIPs were then applied to the selective extraction of SAs from environmental water. The extraction and enrichment were accomplished simultaneously in a single step by simply stirring the mixture of adsorbents and water samples. The Fe3O4@SiO2@MIPs were characterized by scanning electron microscopy, Fourier-transform infrared spectrometry, and vibrating sample magnetometry. The adsorption thermodynamics and kinetics were employed to study the adsorption mechanism of the Fe3O4@SiO2@MIPs. And the matrix effect of the method was evaluated. Calibration curves obtained by analyzing matrix-matched standards show excellent linear relationship (R = 0.9994–0.9999) in the concentration range of 10–1000 ng L−1, and the limits of detection are in the range of 1.4–2.8 ng L−1. The relative standard deviations of intra- and inter-day obtained are in the range of 2.8 to 7.8 and 3.1 to 7.9%, respectively. The proposed method was successfully applied to determine SAs in six environmental water samples, and SAs were detectable in four of them with the concentration from 10.5 to 120.2 ng L−1.
Co-reporter:Tianyu Zhou, Jie Ding, Ling Ni, Jia Yu, Huiyu Li, Hong Ding, Yanhua Chen, Lan Ding
Journal of Chromatography A 2017 Volume 1497(Volume 1497) pp:
Publication Date(Web):12 May 2017
DOI:10.1016/j.chroma.2017.03.069
•Fe3O4@NH2 were first introduced to prepare magnetic superhydrophilic molecular imprinted resins (MMIRs).•Preparation method was based on one-pot condensation of resorcinol, melamine and formaldehyde.•Product yield is higher.•Preparation and extraction process are simple, efficient and fast.•Application of MMIRs for the determination of triazines in aqueous samples combined HPLC–MS/MS.In this work, magnetic superhydrophilic molecularly imprinted resins (MMIRs) were prepared for the determination of triazines in aqueous samples combined HPLC–MS/MS. The amino functionalized magnetic nanoparticles were introduced into superhydrophilic molecularly imprinted resins based on one-pot condensation of resorcinol, melamine and formaldehyde. The obtained MMIRs exhibited magnetic responsiveness, superhydrophilic and selective feature. The MMIRs were directly used as adsorbents for selective enrichment and separation of six triazines in juice and lake samples under an applied magnetic field. The detection limits of triazines are in the range of 0.02–0.07 μg L−1 (except for simazine, 0.38 μg L−1). At the spiked level (5 μg L−1), the recoveries are in the range of 85–101% with the RSDs ≤7%. This work provided a novel and efficient approach for the detection of triazines in aqueous samples.
Co-reporter:Ping Zhang, Jie Ding, Juan Hou, Li Zhao, Yanhua Chen, Lan Ding
Microchemical Journal 2017 Volume 133(Volume 133) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.microc.2017.04.006
•A method based on DMAE-MSPD has been first proposed.•The method combined extraction and clean-up in a single step.•Microwave energy was introduced into the elution process of MSPD.•The method can improve the extraction efficiency, simplify the operation procedure and reduce the solvent consumption.•Fifteen samples can be treated simultaneously in 4 min.Chlorfenapyr and abamectin are two insecticides used commonly in rice-planting to control insects and mites. The residue remained in rice present potential health hazard to consumers. To realize the accurate determination of chlorfenapyr and abamectin in rice samples, a method based on dynamic microwave assisted extraction (DMAE) coupled with matrix solid phase dispersion (MSPD) was established and validated. In the proposed method, microwave energy was introduced into the elution process of MSPD and therefore improved the extraction efficiency. Different parameters affecting the extraction efficiency were studied and optimized, including type of dispersing sorbent, ratio of dispersing sorbent to sample, type of clean-up sorbents, microwave power, extraction solvent, volumes and flow rate of extraction solvent. Under optimal conditions, the interference in rice extract were removed effectively, moreover, the extraction and clean-up were combined in a single step and 15 samples were treated simultaneously with in 4 min. Low limits of detection (0.8 ng g− 1) for chlorfenapyr and abamectin were obtained. The RSDs of intra- and inter-day were in the range of 2.6 to 8.1%. The recoveries of chlorfenapyr and abamectin from rice samples at spiking levels of 5, 50 and 100 ng g− 1 were 92.1–96.5% and 88.6–91.0%, respectively. Finally, the proposed method was successfully applied to analyze chlorfenapyr and abamectin in six rice samples, and satisfactory results were obtained.
Co-reporter:Long Wang, Yidan Bi, Juan Hou, Huiyu Li, Yuan Xu, Bo Wang, Hong Ding, Lan Ding
Talanta 2016 Volume 160() pp:268-275
Publication Date(Web):1 November 2016
DOI:10.1016/j.talanta.2016.07.020
•Green synthesis of carbon dots from wool.•The synthetic method was clean and need not any additives, such as acids, bases, salts, or other toxic reagents.•Detection of glyphosate based on the inner filter effect.•This sensor exhibited superior accuracy and sensitivity for glyphosate.•The established method were employed to detect glyphosate in cereal samples.In this work, we reported a green route for the fabrication of fluorescent carbon dots (CDs). Wool, a kind of nontoxic and natural raw material, was chosen as the precursor to prepare CDs via a one-step microwave-assisted pyrolysis process. Compared with previously reported methods for preparation of CDs based on biomass materials, this method was simple, facile and free of any additives, such as acids, bases, or salts, which avoid the complicated post-treatment process to purify the CDs. The CDs have a high quantum yield (16.3%) and their fluorescence could be quenched by silver nanoparticles (AgNPs) based on inner filter effect (IFE). The presence of glyphosate could induce the aggregation of AgNPs and thus result in the fluorescence recovery of the quenched CDs. Based on this phenomenon, we constructed a fluorescence system (CDs/AgNPs) for determination of glyphosate. Under the optimized conditions, the fluorescence intensity of the CDs/AgNPs system was proportional to the concentration of glyphosate in the range of 0.025–2.5 μg mL−1, with a detection limit of 12 ng mL−1. Furthermore, the established method has been successfully used for glyphosate detection in the cereal samples with satisfactory results.
Co-reporter:Juan Hou, Huiyu Li, Long Wang, Ping Zhang, Tianyu Zhou, Hong Ding, Lan Ding
Talanta 2016 Volume 146() pp:34-40
Publication Date(Web):1 January 2016
DOI:10.1016/j.talanta.2015.08.024
•Microwave heating technique was firstly applied to the efficient preparation of CDs@MIPs.•The reaction time was shortened and the experimental procedure was simplified.•The sensor based on CDs@MIPs exhibited high sensitivity and selectivity.•The proposed eco-friendly sensor was able to determine trace Tc in milk samples with satisfactory results.In this paper, a novel, selective and eco-friendly sensor for the detection of tetracycline was developed by grafting imprinted polymers onto the surface of carbon quantum dots. A simple microwave-assisted approach was utilized to fabricate the fluorescent imprinted composites rapidly for the first time, which could shorten the polymerization time and simplify the experimental procedure dramatically. The novel composites not only demonstrated excellent fluorescence stability and special binding sites, but also could selectively accumulate target analytes. Under optimal conditions, the relative fluorescence intensity of the composites decreased linearly with increasing the concentration of tetracycline from 20 nM to 14 µM. The detection limit of tetracycline was 5.48 nM. The precision and reproducibility of the proposed sensor were also acceptable. Significantly, the practicality of this ultrasensitive sensor for tetracycline detection in milk was further validated, revealing the advantages of simplicity, sensitivity, selectivity and low cost. This approach combines the high selective adsorption property of molecular imprinted polymers and the sensitivity of fluorescence detection. It is envisioned that the development of fluorescent molecularly imprinted composites will offer a new way of thinking for rapid analysis in complex samples.
Co-reporter:Juan Hou, Long Wang, Ping Zhang, Yuan Xu and Lan Ding
Chemical Communications 2015 vol. 51(Issue 100) pp:17768-17771
Publication Date(Web):16 Oct 2015
DOI:10.1039/C5CC08152A
Herein, we present a one-pot microwave-assisted preparative method for water-soluble carbon dots (CDs) in an immiscible system. CDs demonstrated uniform morphology, high quantum yield and excitation-independent fluorescence emission. Moreover, we first reported the observation of thermally activated delayed fluorescence from CDs.
Co-reporter:Juan Hou, Fengshuang Zhang, Xu Yan, Long Wang, Jin Yan, Hong Ding, Lan Ding
Analytica Chimica Acta 2015 Volume 859() pp:72-78
Publication Date(Web):15 February 2015
DOI:10.1016/j.aca.2014.12.021
•Carbon quantum dots-based probe was used for detection of GSH, Cys or His.•The fluorescence of CQDs was quenched by Hg(II) and then recovered by GSH, Cys or His.•No further surface modification or purification of CQDs was required.•This sensor exhibits superior accuracy and sensitivity.•The proposed method was simple in design, fast in operation.In this paper, we presented a novel, rapid and highly sensitive sensor for glutathione (GSH), cysteine (Cys) and histidine (His) based on the recovered fluorescence of the carbon quantum dots (CQDs)–Hg(II) system. The CQDs were synthesized by microwave-assisted approach in one pot according to our previous report. The fluorescence of CQDs could be quenched in the presence of Hg(II) due to the coordination occurring between Hg(II) and functional groups on the surface of CQDs. Subsequently, the fluorescence of the CQDs–Hg(II) system was recovered gradually with the addition of GSH, Cys or His due to their stronger affinity with Hg(II). A good linear relationship was obtained from 0.10 to 20 μmol L−1 for GSH, from 0.20 to 45 μmol L−1 for Cys and from 0.50 to 60 μmol L−1 for His, respectively. This method has been successfully applied to the trace detection of GSH, Cys or His in human serum samples with satisfactory results. The proposed method was simple in design and fast in operation, which demonstrated great potential in bio-sensing fields.
Co-reporter:Qi Zhao, Huiyu Li, Yang Xu, Fengshuang Zhang, Jiahui Zhao, Long Wang, Juan Hou, Hong Ding, Yi Li, Haiyan Jin, Lan Ding
Journal of Chromatography A 2015 Volume 1376() pp:26-34
Publication Date(Web):9 January 2015
DOI:10.1016/j.chroma.2014.12.021
•Single-hole h-MIMs which could recognize triazines were prepared for the first time.•The adsorption sites were located on inner and outer surfaces of the MMIPs.•The adsorption rate of the h-MIMs has been improved greatly.•The synthesis mechanism of the h-MIMs has been presented.Single-hole hollow molecularly imprinted microspheres (h-MIMs) were prepared by hard template method and applied to extract six triazine pesticides in cereal samples, followed by HPLC-MS/MS detection. The synthesis mechanism of the h-MIMs has been studied. The h-MIMs exhibited bigger specific surface area and much higher binding capacity than the molecularly imprinted polymers prepared by precipitation polymerization (p-MIPs) and surface polymerization (s-MIPs). Besides, the adsorption rate of h-MIMs to prometryn was significantly higher than that of p-MIPs and s-MIPs. Owing to the hollow structure of the h-MIMs, more binding cavities were located on the inner and outer surfaces of the h-MIMs, which could facilitate the removal of template molecules from the polymers and the rebinding of the target molecules to the polymers. Under the optimal conditions, the detection limits of triazines are in the range of 0.08-0.16 ng g−1. At the spiked level (5 ng g−1), the recoveries of triazines are in the range of 81 ± 4% to 96 ± 4%. The proposed method was successfully applied to determine six triazines in five cereal samples. Atrazine was found in two rice samples and a wheat sample with the contents of 5.1, 6.7 and 5.6 ng g−1, respectively. Ametryn and prometryn were found in a maize sample with the contents of 7.6 and 7.3 ng g−1, respectively.
Co-reporter:Jiahui Zhao, Xu Yan, Tianyu Zhou, Jing Wang, Huiyu Li, Ping Zhang, Hong Ding and Lan Ding
Journal of Analytical Atomic Spectrometry 2015 vol. 30(Issue 9) pp:1920-1926
Publication Date(Web):07 Jul 2015
DOI:10.1039/C5JA00233H
A rapid and simple multi-throughput dynamic microwave-assisted leaching combined with inductively coupled plasma atomic emission spectrometry determination has been proposed for the simultaneous determination of Cu, Mn, Zn and Pb in soil. The approach combines the advantages of microwave and dynamic leaching technique, and up to five samples could be treated at the same time within 15 min. Nitric acid aqueous solution (20%, w/w) was employed as leachant at a flow rate of 1.5 mL min−1. The leaching condition was optimized systematically and the leaching efficiencies were above 95% for Cu, Mn, Zn, Pb and lower for Cr, Cd, Ni and Co, compared to the conventional method. The leaching efficiencies of Cr, Cd, Ni, and Co could be enhanced to above 60% when a soak process was appended. Relative standard deviations of intra- and inter-day of Cu, Mn, Zn, and Pb were in the range of 1.7–6.3% and 5.0–6.9%, respectively. The proposed method was more rapid than the conventional digestion method and could be an alternative approach for the analysis of heavy metals in complex solid samples. The relatively closed system may have a broad prospect for leaching volatile elements, such as As, Se and Hg if combined with compatible detecting instrumentation.
Co-reporter:Fengshuang Zhang, Juan Hou, Jin Yan, Jiahui Zhao, Qi Zhao, Long Wang, Yi Li and Lan Ding
Analytical Methods 2015 vol. 7(Issue 6) pp:2707-2713
Publication Date(Web):06 Feb 2015
DOI:10.1039/C4AY02688H
In this study, barium sulfate-coated magnetite particles (Fe3O4/BaSO4) for mixed hemimicelles solid-phase extraction, have been successfully synthesized by a chemical coprecipitation method. Fe3O4/BaSO4 modified by sodium dodecyl sulfate (SDS) was applied for the extraction of trimethoprim from environmental water samples. Compared with other substrates, such as alumina, silica and titanium dioxide, Fe3O4/BaSO4 particles have better stability and resistance to acidity and alkalinity. A comprehensive study on the adsorption conditions, such as the amount of SDS, pH value, standing time, desorption solvent and the maximum extraction sample volume was presented. Good recovery (72.3–85.0%) and high concentration factor (800) were achieved using only 0.1 g of Fe3O4/BaSO4 and 20 mg of SDS. The detection and quantification limits of the proposed method were 0.05 and 0.16 μg L−1, respectively. It shows great analytical potential in the preconcentration of organic compounds from large volume water samples.
Co-reporter:Haiyan Chen, Sunil Son, Fengshuang Zhang, Jin Yan, Yi Li, Hong Ding, Lan Ding
Journal of Chromatography B 2015 Volumes 983–984() pp:32-38
Publication Date(Web):1 March 2015
DOI:10.1016/j.jchromb.2015.01.003
•The polymer was prepared by microwave-assisted emulsion polymerization.•The polymerization time was greatly shortened.•The polymer was spherical in shape and exhibited a uniform morphology.•The binding capacity and selectivity of the polymer were studied.•The matrix effect of the method based on the polymer was investigated.In this study, we proposed a rapid and simple method for the preparation of molecularly imprinted polymers (MIPs) by emulsion polymerization. The polymerization process was accelerated by microwave heating, and the reaction time was greatly shortened. The obtained MIPs were spherical in shape and exhibited a uniform morphology. The MIPs with selectivity and high affinity to florfenicol were successfully applied as solid-phase extraction materials to extract and clean up the florfenicol in milk, followed by liquid chromatography–tandem mass spectrometry (LC–MS) analysis. The parameters affecting the performance of extraction and LC–MS analysis were evaluated. The detection limit of the method was 4.1 ng mL−1. The relative standard deviations of intra- and inter-day were in the range of 3.5–4.7% and 3.9–7.5%, respectively.
Co-reporter:Long Wang;Juan Hou;Huiyu Li;Qi Zhao
Journal of Nanoparticle Research 2015 Volume 17( Issue 11) pp:
Publication Date(Web):2015 November
DOI:10.1007/s11051-015-3252-6
In this paper, nitrogen-doped carbon dots (N-CDs) with a quantum yield of 23.6 % were successfully synthesized by microwave pyrolysis of urea using diethylene glycol as the high boiling point reaction medium. The N-CDs were spherical and monodisperse with a size distribution between 1.5 and 5.5 nm. The N-CDs exhibited excellent water-soluble property and remarkable stability under extreme ionic strengths and light illumination. The fluorescence of the N-CDs could be quenched by Fe3+ through the static quenching mechanism, but not by other common metal ions. On this basis, the N-CDs can be used as a facile sensing platform for label-free sensitive and selective detection of Fe3+ in a linear range of 1.6–333.3 μmol L−1, and the detection limit was 0.45 μmol L−1 obtained at a signal-to-noise ratio of 3. Importantly, the N-CDs-based fluorescent probe was successfully applied to the direct analysis of iron contents in human serum samples, which demonstrated potential applications in biological and clinical analysis.
Co-reporter:Juan Hou, Jin Yan, Qi Zhao, Yi Li, Hong Ding and Lan Ding
Nanoscale 2013 vol. 5(Issue 20) pp:9558-9561
Publication Date(Web):08 Aug 2013
DOI:10.1039/C3NR03444E
A simple one-pot microwave-assisted approach has been established for the large-scale preparation of carbon quantum dots (CDs) with excellent water solubility and photoluminescence. The properties and mechanism were demonstrated. Moreover, the CDs have been applied to the detection of tetracycline hydrochloride.
Co-reporter:Hui Wang, Guijie Li, Yiqun Zhang, Haiyan Chen, Qi Zhao, Weitao Song, Yang Xu, Haiyan Jin, Lan Ding
Journal of Chromatography A 2012 Volume 1233() pp:36-43
Publication Date(Web):13 April 2012
DOI:10.1016/j.chroma.2012.02.034
A simple and cost-effective method of dynamic microwave-assisted extraction (DMAE) combined with solidification of floating organic drop (SFO) was developed for determining the five triazine herbicides in cereals. The approach combines the advantages of DMAE and SFO technique, and up to 15 samples can be treated simultaneously in 16 min. Firstly, triazine herbicides were extracted with 1 mL of methanol containing 90 μL of 1-dodecanol and following with 10 mL of water under the action of microwave energy. After that, 1.5 g sodium chloride was added into the obtained extract, and the mixture was centrifuged and cooled. The 1-dodecanol drop which contained the target analytes was solidified and transferred for analysis by HPLC-UV. Limits of detection of the five triazines obtained were in the range of 1.1–1.5 ng g−1. Relative standard deviations of intra- and inter-day tests ranging from 5% to 7% were obtained. The method was successfully applied to the analysis of ten cereals and the recoveries of the triazines for the spiked samples were in the range of 80–102%. The proposed method is an alternative approach to the analysis of triazine herbicides in complex solid samples, being more rapid and simpler compared with the traditional extraction method.Highlights► Cereal samples were extracted by dynamic microwave-assisted extraction technology. ► Triazine herbicides in the extract were enriched by 90 μL of 1-dodecanol. ► Extraction and enrichment were completed in a single step. ► The solidified 1-dodecanol contained triazines was analyzed by HPLC-UV. ► Up to 15 samples can be treated simultaneously in 16 min.
Co-reporter:Hui Wang, Jie Ding, Xiaobo Du, Xin Sun, Ligang Chen, Qinglei Zeng, Yang Xu, Xiaopan Zhang, Qi Zhao, Lan Ding
Food Chemistry 2012 Volume 131(Issue 1) pp:380-385
Publication Date(Web):1 March 2012
DOI:10.1016/j.foodchem.2011.08.056
A method was developed using magnetic strong cation-exchange resin modified with 2,4-dinitrophenylhydrazine (DNPH) for the determination of formaldehyde (HCHO) in fruit juice samples. The procedures of extraction and derivatization were carried out in a single step by stirring the resins and diluted fruit juice with water. When the procedures were completed, the resins adsorbing the HCHO–DNPH derivative were easily separated from the sample matrix by an adscititious magnet. The HCHO–DNPH derivative eluted from the resins was directly determined by high-performance liquid chromatography with UV detector at 360 nm. The limit of detection of the proposed method in fruit juice obtained is 6.0 ng mL−1. In this work, the volume of fruit juice was 5 mL and the amount of MSCX resins was 100 mg, and the resins can be reused 10 times. The relative standard deviations of intra-day and inter-day ranging from 3.9% to 6.1% and from 4.2% to 7.0% are obtained, respectively. The recovery of HCHO in the analysis of spiked fruit juice samples is in the range of 85.7–100.4%.Highlights► In this work, the MSCX resin modified with DNPH was synthesised. ► Extraction and derivatization were carried out in a single step. ► The MSCX resin adsorbing derivative was easily collected by external magnetic field. ► These resins can be reused 10 times.
Co-reporter:Hui Wang, Xiuqing Zhou, Yiqun Zhang, Haiyan Chen, Guijie Li, Yang Xu, Qi Zhao, Weitao Song, Haiyan Jin, and Lan Ding
Journal of Agricultural and Food Chemistry 2012 Volume 60(Issue 41) pp:10343-10351
Publication Date(Web):September 28, 2012
DOI:10.1021/jf303124c
In this work, a simple and fast sample pretreatment method was proposed for determination of steroid hormones in fish tissues by coupling dynamic microwave-assisted extraction with salting-out liquid–liquid extraction. The steroid hormones were successively extracted with acetonitrile and water under the action of microwave energy. Subsequently, the extract was separated into an acetonitrile phase and an aqueous phase with ammonium acetate. The acetonitrile phase containing the target analytes was concentrated and determined by LC–MS/MS. The limits of detection for the steroid hormones were in the range of 0.03–0.15 ng g–1. This method was successfully applied to analyze seven kinds of fish tissues, and the recoveries of the steroid hormones for the spiked samples were in the range of 75.3 ± 4.9% to 95.4 ± 6.2%. Compared with the traditional method, the proposed method could reduce the consumption of the organic solvent, shorten the sample preparation time, and increase the sample throughput.
Co-reporter:Weitao Song;Haoran Cai;Liping Du;Qi Zhao;Haiyan Chen;Guijie Li
Chromatographia 2012 Volume 75( Issue 13-14) pp:747-753
Publication Date(Web):2012 July
DOI:10.1007/s10337-012-2252-2
In this work, microwave-assisted steam extraction (MASE) followed by high performance liquid chromatography is described for the extraction and determination of paeonol in Cortex moutan. This new approach was based on the combination of microwave-assisted extraction and steam distillation. No organic solvent was used and no clean-up step was required before chromatographic analysis. The extraction vessel and water were both under microwave radiation: the water was still heated while the generated steam flowed through the sample. Factors such as collection volume, microwave power, mass of the sample, and mixed proportion of the sample and quartz sand were investigated. The intra- and inter-day relative standard deviation values of <9 % show that the proposed method had good repeatability. To demonstrate its feasibility, the MASE was compared with other extraction methods such as dynamic microwave-assisted extraction, ultrasonic extraction, and steam distillation, and the experimental results show that the MASE was a rapid, effective, and environmentally friendly alternative for the extraction of paeonol in Cortex moutan. Finally, the proposed method was applied on Cortex moutan samples from different producing areas and the results were satisfactory.
Co-reporter:Haoyan Xu;Ligang Chen;Lei Sun;Xin Sun;Xiaobo Du;Jian Wang;Tianyi Wang;Qinglei Zeng;Hui Wang;Yang Xu;Xiaopan Zhang;Lan Ding
Journal of Separation Science 2011 Volume 34( Issue 2) pp:142-149
Publication Date(Web):
DOI:10.1002/jssc.201000365
Abstract
A new method was developed for the determination of six fluoroquinolone antibiotics including fleroxacin, levofloxacin, ciprofloxacin, lomfloxacin, enrofloxacin, and sparfloxacin in chicken breast muscle, in which the extraction and clean-up were performed in one step by microwave irradiation. The mixture of ACN containing 0.3% v/v phosphoric acid/water pH 3 (70:30, v/v) was used as the extraction solution and hexane was used as the clean-up solution. The extract was analyzed by liquid chromatography–tandem mass spectrometry system. The RSDs of intra- and inter-day obtained are in the range of 1.0–10.4 and 3.8–13.6%, respectively. In the three fortified levels of chicken breast muscle (20, 100, and 500 ng/g), the recoveries of fluoroquinolone antibiotics ranging from 66.0 to 97.2% are obtained. The LODs are in the range of 2.7–6.7 ng/g. This method simplifies the process of the sample preparation and reduces the operation errors.
Co-reporter:Hui Wang;Yang Xu;Weitao Song;Qi Zhao;Xiaopan Zhang;Qinglei Zeng;Haiyan Chen;Lan Ding;Nanqi Ren
Journal of Separation Science 2011 Volume 34( Issue 18) pp:2489-2497
Publication Date(Web):
DOI:10.1002/jssc.201100310
Abstract
In the work, a rapid, simple and high-throughput sample preparation method was developed for the determination of sulfonamide (SA) antibiotic residues in chicken breast muscle. The extraction and clean-up were online combined and up to 20 samples can be treated simultaneously in 6 min. The SAs were first extracted with acetonitrile under the action of microwave energy, and then the extract was directly introduced into the SPE column for on-line clean-up and concentration. Subsequently, the SAs eluted from the SPE column were determined by liquid chromatography–tandem mass spectrometry. The precisions of extraction results of 20 samples were in the range of 4.9–7.4%. The limits of detection and quantification obtained were in the range of 2.4–3.6 ng/g and 8.6–11.3 ng/g for SAs, respectively. The recoveries of SAs obtained by analyzing chicken muscles at three fortified levels (10, 50 and 500 ng/g) were in the range of 82.6–93.2%. The results of the validation process prove that the proposed method is suitable for treating numbers of complex samples simultaneously in a short time.
Co-reporter:Haoyan Xu;Tianyi Wang;Qi Zhao;Qinglei Zeng;Hui Wang;Yang Xu
Chromatographia 2011 Volume 74( Issue 3-4) pp:267-274
Publication Date(Web):2011 August
DOI:10.1007/s10337-011-2049-8
An environmentally friendly method for the determination of fluoroquinolone (FQ) antibiotics including enrofloxacin, ciprofloxacin, levofloxacin, fleroxacin and sparfloxacin in four feeds is proposed. Disodium ethylenediaminetetraacetate (EDTA)–Mcllvaine buffer (0.1 mol L−1, pH 4.0) was used as an extracting solvent and the extraction process was accelerated by microwave irradiation. No organic solvents were used in the extraction procedure. The extract obtained was then cleaned up and concentrated by an Oasis hydrophilic–lipophilic balance (HLB) solid-phase extraction cartridge. The relative intra- and inter-day standard deviations obtained were in the range of 3.7–9.1 and 2.1–11.4%, respectively. In the three fortified levels of blank feed sample (30, 100 and 500 ng g−1), recoveries of FQs ranging from 61.1 to 97.9% were obtained. The analytes desorbed from HLB were analyzed by liquid chromatography–tandem mass spectrometry. The limit of detection was in the range of 5.0–9.1 ng g−1. The method presented here can be considered a promising alternative to traditional techniques using shaking or stirring for extraction, being more effective, and producing less pollution.
Co-reporter:Lei Sun, Xin Sun, Xiaobo Du, Yanshan Yue, Ligang Chen, Haoyan Xu, Qinglei Zeng, Hui Wang, Lan Ding
Analytica Chimica Acta 2010 Volume 665(Issue 2) pp:185-192
Publication Date(Web):30 April 2010
DOI:10.1016/j.aca.2010.03.044
In this study, alumina-coated magnetite nanoparticles (Fe3O4/Al2O3 NPs) were synthesized, and they were applied to the analysis of sulfonamides (SAs) including sulfadiazine (SDZ), sulfamerazine (SMR), sulfamethoxazole (SMX), sulfamonomethoxine (SMM), sulfamethoxydiazine (SMD), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX) in different soil samples based on magnetic solid-phase extraction (MSPE). The extraction and concentration process was carried out in a single step by mixing the extraction solvent, magnetic adsorbents and soil sample under ultrasonic action. Then, the adsorbents were isolated from the complicated matrix easily with an external magnetic field. The SAs desorbed from the adsorbents were determined by liquid chromatography–tandem mass spectrometry. Compared with traditional methods, the MSPE method simplified the operation procedure and reduced the analysis time. Under the optimum conditions, the recoveries of SDZ, SMR, SMX, SMM, SMD and SDM by analyzing the five spiked soil samples were between 71% and 93% except for SQX (42–60%). This may be due to the stronger hydrophobic property of SQX. Detection limits of SAs were between 0.37 and 6.74 ng g−1. It was also found that the “aging” effect of SAs contaminated soil could cause the recoveries to decrease.
Co-reporter:Ligang Chen, Xiaopan Zhang, Yang Xu, Xiaobo Du, Xin Sun, Lei Sun, Hui Wang, Qi Zhao, Aimin Yu, Hanqi Zhang, Lan Ding
Analytica Chimica Acta 2010 Volume 662(Issue 1) pp:31-38
Publication Date(Web):3 March 2010
DOI:10.1016/j.aca.2010.01.001
A simple method based on magnetic separation for selective extraction of fluoroquinolones (FQs) from environmental water samples has been developed using magnetic molecularly imprinted polymer (MMIP) as sorbent. The MMIP has been prepared using ciprofloxacin as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linking agent and Fe3O4 magnetite as magnetic component. The polymer has been characterized by scanning electron microscopy, Fourier-transform infrared spectrometry and vibrating sample magnetometry. Various parameters affecting the extraction efficiency were evaluated in order to achieve optimal concentration and reduce non-specific interactions. The analytes desorbed from the polymers were determined by liquid chromatography–tandem mass spectrometry. The matrix effect was evaluated by using different washing solvents for removing interfering compounds from the MMIPs after sample loading. Under the optimal conditions, the linearity of the method obtained is in the range of 20–2000 ng L−1. The detection limits of FQs are in the range of 3.2–6.2 ng L−1. The relative standard deviations of intra- and inter-day tests ranging from 2.5 to 7.2% and from 3.6 to 9.1% are obtained. In all three spiked levels (20, 100 and 200 ng L−1), the recoveries of FQs are in the range of 76.3–94.2%. The proposed method was successfully applied to determine FQs including ciprofloxacin, enrofloxacin, lomefloxacin, levofloxacin, fleroxacin and sparfloxacin in different water samples, such as lake water, river water, primary and final sewage effluent. Ciprofloxacin and fleroxacin were found in primary and final sewage effluent samples with the contents in the range of 26–87 ng L−1.
Co-reporter:Yang Xu, Ligang Chen, Hui Wang, Xiaopan Zhang, Qinglei Zeng, Haoyan Xu, Lei Sun, Qi Zhao, Lan Ding
Analytica Chimica Acta 2010 Volume 661(Issue 1) pp:35-41
Publication Date(Web):19 February 2010
DOI:10.1016/j.aca.2009.12.002
In the work, magnetic strong cation exchange (MSCX) resins were prepared using hydrophobic Fe3O4 magnetite as the magnetically susceptible component, styrene and divinylbenzene as polymeric matrix components, acetyl sulfonate as the sulfonation agent. The resins were successfully applied to the extraction of melamine (MEL) from egg samples. The extraction procedure was carried out in a single step by blending and stirring the sample, extraction solvent and the magnetic resins. The MEL was extracted from the sample matrix then adsorbed onto the resins directly through ion-exchange interaction. When the extraction was completed, the resins with adsorbed analyte were easily separated from the sample matrix by applying an appropriate magnetic field. Main factors affecting the extraction of MEL such as the amount of MSCX resins, extraction time, washing and eluting conditions were optimized. The MEL eluted from the resins was determined by liquid chromatography–tandem mass spectrometry. The linearity of quantification obtained by analyzing matrix-matched standards is in the range of 10–1000 ng g−1. The limit of detection and quantification obtained are 2.6 and 8.8 ng g−1, respectively. The relative standard deviations of intra- and inter-day ranging from 1.6% to 6.5% and from 2.1% to 7.2% are obtained. The recoveries of MEL are in the range of 77.2–99.3%. The proposed method was successfully applied to determine MEL in eggs obtained from different local markets. MEL was detectable with the contents of 43.5 and 234.1 ng g−1 in two samples.
Co-reporter:Ligang Chen, Qi Zhao, Yang Xu, Lei Sun, Qinglei Zeng, Haoyan Xu, Hui Wang, Xiaopan Zhang, Aimin Yu, Hanqi Zhang, Lan Ding
Talanta 2010 Volume 82(Issue 4) pp:1186-1192
Publication Date(Web):15 September 2010
DOI:10.1016/j.talanta.2010.06.031
A green and simple method was developed for determination of sulfonamides (SAs) in soil samples. The procedure was based on the microwave-assisted extraction (MAE) of SAs from soil using non-ionic surfactant Triton X-114 as the extraction medium. Then sodium chloride was added into the MAE extract and the mixture was equilibrated for some time at high temperature. The analytes in the surfactant-rich phase were concentrated with the help of centrifugation and directly analyzed by high performance liquid chromatography with UV detection. None of potentially hazardous organic solvents was used in the whole sample preparation procedure. The significant variables for the performance of extraction and concentration were studied. The limits of detection of SAs obtained are in the range of 3.2–5.7 ng g−1. The relative standard deviations of intra- and inter-day tests ranging from 3.5% to 7.7% and from 4.6% to 9.5% are obtained, respectively. This method was applied to the determination of SAs in some soil samples with different characteristics. The SAs recoveries obtained at fortified level of 100 ng g−1 for these samples are in the range of 81.2–93.7%. The effect of ageing time of spiked soil samples on the SAs recoveries was examined by the proposed method and a method reported in the literature. The recoveries of SAs decreased when the ageing time changed from 1 day to 4 weeks.
Co-reporter:Xiaopan Zhang, Ligang Chen, Yang Xu, Hui Wang, Qinglei Zeng, Qi Zhao, Nanqi Ren, Lan Ding
Journal of Chromatography B 2010 Volume 878(Issue 32) pp:3421-3426
Publication Date(Web):15 December 2010
DOI:10.1016/j.jchromb.2010.10.030
In this work, a rapid and selective method was successfully developed using the magnetic molecularly imprinted polymer (MMIP) as sorbent for the extraction of β-lactam antibiotics (BLAs) from milk samples. The MMIP has been prepared using penicillin V potassium (PENV) as template molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinking agent and Fe3O4 magnetite as magnetic component. The experimental results showed that the MMIP had high affinity and selectivity toward PENV and other structurally related BLAs. The extraction process was carried out in a single step by mixing the extraction solvent, MMIPs and milk samples under ultrasonic action. When the extraction was completed, the MMIPs adsorbing the analytes were separated from the sample matrix by an external magnet. The analytes eluted from the MMIP were analyzed by liquid chromatography–tandem mass spectrometry. For achieving optimal preconcentration and reducing non-specific interactions, various parameters affecting the extraction efficiency such as extraction mode, extraction solvent, the amount of MMIPs, extraction time, washing solution and eluting solution were comprehensively evaluated. Under the optimal conditions, the detection limits of BLAs are in the range of 1.6–2.8 ng mL−1. The relative standard deviations of intra- and inter-day ranging from 3.2% to 8.3% and from 3.6% to 9.8% are obtained, respectively. The method was applied to determine BLAs including PENV, amoxicillin and oxacillin in five milk samples from different provenances. The recoveries of BLAs in these samples from 71.6% to 90.7% are obtained.
Co-reporter:Lei Sun, Chuanzhou Zhang, Ligang Chen, Jun Liu, Haiyan Jin, Haoyan Xu, Lan Ding
Analytica Chimica Acta 2009 Volume 638(Issue 2) pp:162-168
Publication Date(Web):13 April 2009
DOI:10.1016/j.aca.2009.02.039
In this study, a new type of alumina-coated magnetite nanoparticles (Fe3O4/Al2O3 NPs) modified by the surfactant sodium dodecyl sulfate (SDS) has been successfully synthesized and applied for extraction of trimethoprim (TMP) from environmental water samples based on mixed hemimicelles solid-phase extraction (MHSPE). The coating of alumina on Fe3O4 NPs not only avoids the dissolving of Fe3O4 NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. Due to the high surface area of these new sorbents and the excellent adsorption capacity after surface modification by SDS, satisfactory concentration factor and extraction recoveries can be produced with only 0.1 g Fe3O4/Al2O3 NPs. Main factors affecting the adsolubilization of TMP such as the amount of SDS, pH value, standing time, desorption solvent and maximal extraction volume were optimized. Under the selected conditions, TMP could be quantitatively extracted. The recoveries of TMP by analyzing the four spiked water samples were between 67 and 86%, and the relative standard deviation (RSD) ranged from 2 to 6%. Detection and quantification limits of the proposed method were 0.09 and 0.24 μg L−1, respectively. Concentration factor of 1000 was achieved using this method to extract 500 mL of different environmental water samples. Compared with conventional SPE methods, the advantages of this new Fe3O4/Al2O3 NPs MHSPE method still include easy preparation and regeneration of sorbents, short times of sample pretreatment, high extraction yields, and high breakthrough volumes. It shows great analytical potential in preconcentration of organic compounds from large volume water samples.
Co-reporter:Ligang Chen, Jun Liu, Qinglei Zeng, Hui Wang, Aimin Yu, Hanqi Zhang, Lan Ding
Journal of Chromatography A 2009 Volume 1216(Issue 18) pp:3710-3719
Publication Date(Web):1 May 2009
DOI:10.1016/j.chroma.2009.02.044
Magnetic molecularly imprinted polymers were prepared using hydrophobic Fe3O4 magnetite as the magnetically susceptible component, oxytetracycline as template molecule, methacrylic acid as functional monomer, and styrene and divinylbenzene as polymeric matrix components. The polymers were applied to the separation of tetracycline antibiotics from egg and tissue samples. The extraction and clean-up procedures were carried out in a single step by blending and stirring the sample, extraction solvent and polymers. The analytes can be transferred from the sample matrix to the polymers directly or through the extraction solvent as medium. When the extraction was complete, the polymers adsorbing the analytes were easily separated from the sample matrix by an adscititious magnet. The analytes eluted from the polymers were determined by liquid chromatography–tandem mass spectrometry. The recoveries ranging from 72.8% to 96.5% were obtained with relative standard deviations in the range of 2.9–12.3%. The limit of detection was less than 0.2 ng g−1. The feasibility of this method was validated by analysis of incurred egg and tissue samples, and the results were compared with those obtained by the classical method in which solvent extraction, centrifugation, and subsequent clean-up and concentration by solid-phase extraction were applied. The proposed method reduced the complicacy of classical method and improved the reliability of method.
Co-reporter:Ligang Chen, Haiyan Jin, Haoyan Xu, Lei Sun, Aimin Yu, Hanqi Zhang and Lan Ding
Journal of Agricultural and Food Chemistry 2009 Volume 57(Issue 10) pp:3989-3994
Publication Date(Web):April 8, 2009
DOI:10.1021/jf900136x
A rapid technique based on microwave-assisted extraction (MAE) coupled online with derivatization, restricted access material cleanup, and high-performance liquid chromatography (HPLC) was developed for the determination of formaldehyde in aquatic products. Formaldehyde was first extracted with water under the action of microwaves and then directly introduced into a derivatization reservoir containing 2,4-dinitrophenylhydrazine (DNPH). The formaldehyde−DNPH derivative (100 μL) was loaded into a restricted access material (RAM) precolumn for online cleanup. Subsequently, the analyte was transferred from the precolumn to an analytical column and determined by UV absorption spectrum at 352 nm. The limit of detection (LOD) was 0.27 mg kg−1. The intraday and interday precisions expressed as RSDs were 3.5% and 5.0%, respectively. This method was applied to determine the presence of formaldehyde in various aquatic products. The results were in agreement with those obtained by the state standard method (steam-distillation and offline HPLC analysis) used in China and higher than those obtained by the online ultrasound-assisted extraction (UAE) method. The recoveries obtained by analyzing 11 spiked aquatic products were in the range of 70.0%−105.0%. The online technique was demonstrated to be rapid with little consumption of samples and reagents.
Co-reporter:Ligang Chen, Xiaopan Zhang, Lei Sun, Yang Xu, Qinglei Zeng, Hui Wang, Haoyan Xu, Aimin Yu, Hanqi Zhang and Lan Ding
Journal of Agricultural and Food Chemistry 2009 Volume 57(Issue 21) pp:10073-10080
Publication Date(Web):October 9, 2009
DOI:10.1021/jf902257d
A fast and selective method was developed for the determination of sulfonamides (SAs) in honey based on magnetic molecularly imprinted polymer. The extraction was carried out by blending and stirring the sample, extraction solvent and polymers. When the extraction was complete, the polymers, along with the captured analytes, were easily separated from the sample matrix by an adscititious magnet. The analytes eluted from the polymers were determined by liquid chromatography−tandem mass spectrometry. Under the optimal conditions, the detection limits of SAs are in the range of 1.5−4.3 ng g−1. The relative standard deviations of intra- and interday ranging from 3.7% to 7.9% and from 4.3% to 9.9% are obtained, respectively. The proposed method was successfully applied to determine SAs including sulfadiazine, sulfamerazine, sulfamethoxydiazine, sulfamonomethoxine, sulfadimethoxine, sulfamethoxazole and sulfaquinoxaline in different honey samples. The recoveries of SAs in these samples from 67.1% to 93.6% were obtained.
Co-reporter:Ligang Chen;Qinglei Zeng;Xiaobo Du;Xin Sun
Analytical and Bioanalytical Chemistry 2009 Volume 395( Issue 5) pp:
Publication Date(Web):2009 November
DOI:10.1007/s00216-009-3097-x
In this work, a new method was developed for the determination of melamine (MEL) in animal feed. The method was based on the on-line coupling of dynamic microwave-assisted extraction (DMAE) to strong cation-exchange (SCX) resin clean-up. The MEL was first extracted by 90% acidified methanol aqueous solution (v/v, pH = 3) under the action of microwave energy, and then the extract was cooled and passed through the SCX resin. Thus, the protonated MEL was retained on the resin through ion exchange interaction and the sample matrixes were washed out. Some obvious benefits were achieved, such as acceleration of analytical process, together with reduction in manual handling, risk of contamination, loss of analyte, and sample consumption. Finally, the analyte was separated by a liquid chromatograph with a SCX analytical column, and then identified and quantitatived by a tandem mass spectrometry with positive ionization mode and multiple-reaction monitoring. The DMAE parameters were optimized by the Box–Behnken design. The linearity of quantification obtained by analyzing matrix-matched standards is in the range of 50–5,000 ng g−1. The limit of detection and limit of quantification obtained are 12.3 and 41.0 ng g−1, respectively. The mean intra- and inter-day precisions expressed as relative standard deviations with three fortified levels (50, 250, and 500 ng g−1) are 5.1% and 7.3%, respectively, and the recoveries of MEL are in the range of 76.1–93.5%. The proposed method was successfully applied to determine MEL in different animal feeds obtained from the local market. MEL was detectable with the contents of 279, 136, and 742 ng g−1 in three samples.
Co-reporter:Ligang Chen, Qinglei Zeng, Hui Wang, Rui Su, Yang Xu, Xiaopan Zhang, Aimin Yu, Hanqi Zhang, Lan Ding
Analytica Chimica Acta 2009 648(2) pp: 200-206
Publication Date(Web):
DOI:10.1016/j.aca.2009.07.010
Co-reporter:Ligang Chen, Haiyan Jin, Liguang Wang, Lei Sun, Haoyan Xu, Lan Ding, Aimin Yu, Hanqi Zhang
Journal of Chromatography A 2008 Volume 1192(Issue 1) pp:89-94
Publication Date(Web):23 May 2008
DOI:10.1016/j.chroma.2008.03.037
An on-line method was developed for the extraction, derivatization and determination of formaldehyde in textile samples. Formaldehyde was first extracted with water by ultrasound assisted, and directly introduced into a derivatization column which was packed with a moderately sulfonated cation-exchange resin. The resin used as solid support for the derivatization was charged with 2,4-dinitrophenylhydrazine (DNPH) previously. The formaldehyde DNPH derivative was eluted with the chromatographic mobile phase into an analytical column for the separation, and then monitored by UV detector. The maximum extraction yield was achieved when the extraction vessel was located at 10 mm from the ultrasonic source and 10 mg textile sample was extracted with 5 mL pure water at a flow rate of 1.0 mL min−1 at 50 °C. The detection limit of the proposed method was 0.06 mg kg−1. This method was applied to the determination of formaldehyde in different textile samples, and compared with the state standard method (off-line spectrophotometry) used in China. The similar contents of formaldehyde were obtained for most samples by the two methods, but little higher for some samples obtained by the proposed method. The average relative standard deviation (RSD) obtained by the on-line method was 3.2% which is lower than 29.5% obtained by the standard method.
Co-reporter:Ligang Chen, Haiyan Jin, Lan Ding, Huarong Zhang, Juan Li, Chenling Qu, Hanqi Zhang
Separation and Purification Technology 2008 Volume 59(Issue 1) pp:50-57
Publication Date(Web):1 February 2008
DOI:10.1016/j.seppur.2007.05.025
An apparatus for extraction of flavonoids from Herba Epimedii has been constructed which utilizes a microwave technique for heating in a dynamic mode. A TM010 microwave resonance cavity was applied to concentrate the microwave energy; the power needed to achieve efficient extraction was significantly reduced. The method has been compared with other extraction methods, such as pressurized microwave-assisted extraction (PMAE), ultrasonic extraction (UE), heat reflux extraction (RE) and Soxhlet extraction (SOX). The four flavonoids in extract were identified by HPLC–MS. The influence of extraction parameters on the extraction yield of flavonoids has been evaluated by comparison with the peak areas of HPLC-DAD spectra in the different extraction methods. The results showed that the extraction yield of flavonoids in Herba Epimedii obtained by dynamic microwave-assisted extraction (DMAE) was higher than that obtained by UE, RE and SOX, and the extraction time is dramatically reduced. The extraction yield obtained by DMAE is similar to that obtained by PMAE. But the flavonoids in Herba Epimedii would not decompose easily when increasing the extraction time in DMAE. This is the benefit of dynamic extraction system which can transfer the analytes extracted from the sample matrix with flowed fresh solvent to the out of extraction vessel.
Co-reporter:Jiantao Li, Ligang Chen, Xiao Wang, Haiyan Jin, Lan Ding, Kun Zhang, Hanqi Zhang
Talanta 2008 Volume 75(Issue 5) pp:1245-1252
Publication Date(Web):15 June 2008
DOI:10.1016/j.talanta.2008.01.027
An automated system using on-line solid-phase extraction (SPE) high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was developed for the determination of tetracyclines (TCs), such as tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), metacycline (MC), and doxycycline (DC) in honey. One milliliter diluted honey sample was injected into a conditioned C18 SPE column and the matrix was washed out with water for 3 min. By rotation of the switching valve, TCs were eluted and transferred to the analytical column by the chromatographic mobile phase. Chromatographic conditions were optimized. TCs were separated in less than 8 min with a gradient elution using a mixture of 0.8% formic acid and acetonitrile. The UV detection was performed at 365 nm. The conditions for on-line SPE, including solvent and total time for loading sample and washing matrix were also optimized. Time for extraction and separation decreased greatly. For the five kinds of TCs, the limits of detection (LODs) at a signal-to-noise of 3 ranged from 5 to 12 ng g−1. The relative standard deviations (R.S.D.) for the determination of TCs ranged from 3.4 to 7.1% within a day and ranged from 3.2 to 8.9% in 3 days, respectively.
Co-reporter:Ligang Chen, Lan Ding, Aimin Yu, Ruilan Yang, Xiupin Wang, Jiantao Li, Haiyan Jin, Hanqi Zhang
Analytica Chimica Acta 2007 Volume 596(Issue 1) pp:164-170
Publication Date(Web):16 July 2007
DOI:10.1016/j.aca.2007.05.063
This paper describes a new method for the determination of total flavonoids in Platycladus orientalis (L.) Franco. The method was based on dynamic microwave-assisted extraction (DMAE) coupled with on-line derivatization and ultraviolet–visible (UV–vis) detection. The influence of the experimental conditions was tested. Maximum extraction yield was achieved using 80% aqueous methanol of extraction solvent; 80 W of microwave output power; 5 min of extraction time; 1.0 mL min−1 of extraction solvent flow rate. The derivatization reaction between aluminium chloride and flavonoid is one of the most sensitive and selective reactions for total flavonoids determination. The optimized derivatization conditions are as follows: derivatization reagent 1.5% aluminium chloride methanol solution; reaction coil length 100 cm; derivatization reagent flow rate 1.5 mL min−1. The detection and quantification limits obtained are 0.28 and 0.92 mg g−1, respectively. The intra-day and inter-day precisions (R.S.D.) obtained are 1.5% and 4.6%, respectively. Mean recovery is 98.5%. This method was successfully applied to the determination of total flavonoids in P. orientalis (L.) Franco and compared with heat reflux extraction. The results showed that the higher extraction yield of total flavonoids was obtained by DMAE with shorter extraction time (5 min) and small quantity of extraction solvent (5 mL).
Co-reporter:Lei Sun, Ligang Chen, Xin Sun, Xiaobo Du, Yanshan Yue, Dongqing He, Haoyan Xu, Qinglei Zeng, Hui Wang, Lan Ding
Chemosphere (November 2009) Volume 77(Issue 10) pp:1306-1312
Publication Date(Web):1 November 2009
DOI:10.1016/j.chemosphere.2009.09.049
The magnetic mixed hemimicelles solid-phase extraction (MMHSPE), based on the adsorption of cation surfactant octadecyltrimethylammonium bromide (OTMABr) onto magnetite nanoparticles (Fe3O4 NPs) to form mixed hemimicelles, was proposed for the preconcentration of several sulfonamides (SAs) compounds including sulfamethoxazole (SMX), sulfamethoxydiazine (SMD), sulfadimethoxine (SDM) and sulfaquinoxaline (SQX) from environmental water samples. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of OTMABr-coated Fe3O4 NPs with an adscititious magnet. Mixed hemimicelles formed on the surface of Fe3O4 NPs by OTMABr showed great adsorptive tendency towards analytes. The OTMABr-coated Fe3O4 NPs adsorbents were easy to be prepared, low cost and environmentally friendly. A comprehensive study on the adsorption conditions such as the amount of the surfactant, the solution pH, the desorption condition and the maximum extraction sample volume were optimized. A concentration factor of 1000 was achieved by the extraction of 500 mL of environmental water samples using MMHSPE. Detection limits obtained for SMX, SMD, SDM and SQX were 0.026, 0.024, 0.033 and 0.030 μg L−1, respectively. Good recoveries (70–102%) with low relative standard deviations (1–6%) were achieved in analyzing spiked water samples. Low concentration of SQX was found in hospital primary and final sewage effluent sample.
Co-reporter:Juan Hou, Long Wang, Ping Zhang, Yuan Xu and Lan Ding
Chemical Communications 2015 - vol. 51(Issue 100) pp:NaN17771-17771
Publication Date(Web):2015/10/16
DOI:10.1039/C5CC08152A
Herein, we present a one-pot microwave-assisted preparative method for water-soluble carbon dots (CDs) in an immiscible system. CDs demonstrated uniform morphology, high quantum yield and excitation-independent fluorescence emission. Moreover, we first reported the observation of thermally activated delayed fluorescence from CDs.
Co-reporter:Jiahui Zhao, Xu Yan, Tianyu Zhou, Jing Wang, Huiyu Li, Ping Zhang, Hong Ding and Lan Ding
Journal of Analytical Atomic Spectrometry 2015 - vol. 30(Issue 9) pp:NaN1926-1926
Publication Date(Web):2015/07/07
DOI:10.1039/C5JA00233H
A rapid and simple multi-throughput dynamic microwave-assisted leaching combined with inductively coupled plasma atomic emission spectrometry determination has been proposed for the simultaneous determination of Cu, Mn, Zn and Pb in soil. The approach combines the advantages of microwave and dynamic leaching technique, and up to five samples could be treated at the same time within 15 min. Nitric acid aqueous solution (20%, w/w) was employed as leachant at a flow rate of 1.5 mL min−1. The leaching condition was optimized systematically and the leaching efficiencies were above 95% for Cu, Mn, Zn, Pb and lower for Cr, Cd, Ni and Co, compared to the conventional method. The leaching efficiencies of Cr, Cd, Ni, and Co could be enhanced to above 60% when a soak process was appended. Relative standard deviations of intra- and inter-day of Cu, Mn, Zn, and Pb were in the range of 1.7–6.3% and 5.0–6.9%, respectively. The proposed method was more rapid than the conventional digestion method and could be an alternative approach for the analysis of heavy metals in complex solid samples. The relatively closed system may have a broad prospect for leaching volatile elements, such as As, Se and Hg if combined with compatible detecting instrumentation.
