Co-reporter:Xing-Yu Long, Zi-Jin Zhang, Jia-Yuan Li, Dong Sheng, and Hong-Zhen Lian
Analytical Chemistry October 3, 2017 Volume 89(Issue 19) pp:10446-10446
Publication Date(Web):September 4, 2017
DOI:10.1021/acs.analchem.7b02476
A facile solvothermal method for the synthesis of multifunctional magnetic CuFeMnO4 nanospheres affinity probe (NSAP) with controllable morphology and size was developed for the first time. The CuFeMnO4 nanospheres combine the brilliant features of Cu2+, Fe3+, and Mn2+ ions, so their multifunction performances are embodied by strong coordination to carboxyl and amine groups of peptides (Cu2+ and Fe3+), special affinity to phosphate groups of phosphopeptides (Fe3+ and Mn2+), and high magnetic responsiveness in a magnetic field. Their potential as an affinity probe was evaluated for highly effective enrichment, rapid magnetic separation of low-abundance peptides (neutral condition), and effective selective capture of phosphopeptides (acid condition) from various complex biosamples. Notably, CuFeMnO4 NSAP was explored for highly selective capture and isolation of phosphopeptides from A549 cells after exposure to ZnO nanoparticles for different times. Consequently, we put forward a new nanospinel ferrite-based protocol here to analyze and identify the phosphoproteins/phosphopeptides involved in cellular signaling pathways in response to exogenous stimulation.
Co-reporter:Xing-yu Long;Zi-jin Zhang;Jia-yuan Li;Dong Sheng
Chemical Communications 2017 vol. 53(Issue 33) pp:4620-4623
Publication Date(Web):2017/04/20
DOI:10.1039/C7CC00540G
This work presents a sequential enrichment protocol, based on two self-designed cerium-based nanocomposite affinity probes, which not only can effectively separate phosphopeptides from non-phosphopeptides but can also selectively differentiate mono- and multi-phosphopeptides for direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOF MS) analysis.
Co-reporter:Caiyun Jiang, Xiaoyuan Ma, Maoyun Xue, Hong-zhen Lian
Talanta 2017 Volume 174(Volume 174) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.talanta.2017.06.010
•P(NIPAM-NVP)/GNRs composites were prepared using gallic acid as the reducing agent.•In situ formation of P(NIPAM-NVP)/GNRs was easily achieved without acidification.•Hot spots generated for the thermoresponsive properties of the hydrogel films.•The capture and preconcentration of diquat were realized by P(NIPAM-NVP) hydrogels.•This material was used as SERS substrate for rapid and sensitive detection of diquat.Gallic acid (GA) was employed as a reducing agent for facile in situ preparation of gold nanorods (GNRs) in thermoresponsive P(NIPAM-NVP) hydrogel films. Based on the surface-enhanced Raman scattering (SERS) effect of GNRs and the enrichment effect of thermoresponsive hydrogel film on test molecules through a shrinkage process, the obtained P(NIPAM-NVP)/GNRs composites have been used as SERS substrate for the rapid detection of diquat. The influences of substrate pre-treatment, laser wavelength, and sample treatment method on diquat determination have been investigated comprehensively. The results showed the composite material to be a good SERS substrate for highly sensitive detection and a promising preconcentration matrix of diquat. The limit of detection of the proposed protocol was estimated to be 2.7×10−13 mol L−1 for diquat. Notably, diquat could be concentrated with the enrichment factor of about 4 after three times swelling-shrinking processes of the hydrogel film.Download high-res image (183KB)Download full-size image
Co-reporter:Chao Liang, Jun-qin Qiao, Hong-zhen Lian
Journal of Chromatography A 2017 Volume 1528(Volume 1528) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.chroma.2017.10.064
•RPLC based logP determination methods have been revisited comprehensively.•Isocratic and gradient RPLC methods were conducted in the same lab and assessed.•Different lipophilicity indexes were compared for logP/logD determination.•Ion-pair RPLC method was explored for studying logD of sulfonic acids.Reversed-phase liquid chromatography (RPLC) based octanol-water partition coefficient (logP) or distribution coefficient (logD) determination methods were revisited and assessed comprehensively. Classic isocratic and some gradient RPLC methods were conducted and evaluated for neutral, weak acid and basic compounds. Different lipophilicity indexes in logP or logD determination were discussed in detail, including the retention factor logkw corresponding to neat water as mobile phase extrapolated via linear solvent strength (LSS) model from isocratic runs and calculated with software from gradient runs, the chromatographic hydrophobicity index (CHI), apparent gradient capacity factor (kg’) and gradient retention time (tg). Among the lipophilicity indexes discussed, logkw from whether isocratic or gradient elution methods best correlated with logP or logD. Therefore logkw is recommended as the preferred lipophilicity index for logP or logD determination. logkw easily calculated from methanol gradient runs might be the main candidate to replace logkw calculated from classic isocratic run as the ideal lipophilicity index. These revisited RPLC methods were not applicable for strongly ionized compounds that are hardly ion-suppressed. A previously reported imperfect ion-pair RPLC method was attempted and further explored for studying distribution coefficients (logD) of sulfonic acids that totally ionized in the mobile phase. Notably, experimental logD values of sulfonic acids were given for the first time. The IP-RPLC method provided a distinct way to explore logD values of ionized compounds.
Co-reporter:Xing-Yu Long, Jia-Yuan Li, Dong Sheng, Hong-Zhen Lian
Talanta 2017 Volume 166() pp:36-45
Publication Date(Web):1 May 2017
DOI:10.1016/j.talanta.2017.01.025
•The synthesis of MnFe2O4 particles is described.•The characterization of synthetized MnFe2O4 was carried out.•The mechanism for the formation of MnFe2O4 was purposed.•MnFe2O4 was used as novel adsorbent for phosphopeptide enrichment.The spinel-type magnetic manganese ferrite (MnFe2O4) microspheres synthesized by simple solvothermal method were used as a novel adsorbent for selective enrichment and effective isolation of phosphopeptides. The uniform MnFe2O4 magnetic affinity microspheres (MAMSs) had a narrow particle size distribution between 250 and 260 nm, and displayed superparamagnetism with a saturation magnetization value of 67.0 emu/g. Comprehensively, the possible formation mechanism of MnFe2O4 microspheres with ferric and manganous sources as dual precursors was elucidated by comparison with those of Fe3O4 nanoparticles and MnOOH nanosheets respectively with either ferric or manganous source as single precursor. It was suggested that the spherical or sheet nanostructures could be achieved via secondary recrystallization or Ostwald ripening. The MnFe2O4 MAMSs probe exhibited excellent dispersibility in aqueous solution, and rapid magnetic separation within 15 s, as well as good reusability. More importantly, MnFe2O4 was highly selective for phosphopeptides because of the strong coordination interaction between metal ions (Fe3+ and Mn2+) and phosphate groups of phosphopeptdies. This high specificity was demonstrated by effectively enriching phosphopeptides from digest mixture of β-casein and bovine serum albumin (BSA) with high content of non-phosphopeptides, and embodied further in phosphopeptides enrichment from non-fat milk digests and human serum. Consequently, the prepared MnFe2O4 affinity materials are expected to possess great potential in phosphoproteome research.
Co-reporter:Jin-cheng Zhao, Qing-yun Zhu, Ling-yu Zhao, Hong-zhen Lian and Hong-yuan Chen
Analyst 2016 vol. 141(Issue 16) pp:4961-4967
Publication Date(Web):03 Jun 2016
DOI:10.1039/C6AN00957C
A novel strategy for the preparation of an aptamer based organic–inorganic hybrid affinity monolithic column was developed successfully using gold nanoparticles (GNPs) as an intermediary for a sandwich structure to realize the functional modification of the surface of the monolithic matrix. This monolithic matrix was facilely pre-synthesized via one-step co-condensation. Due to the high surface-to-volume ratio of GNPs and the large specific surface area of the hybrid matrix, the average coverage density of aptamers on the hybrid monolith reached 342 pmol μL−1. With the combination of an aptamer based hybrid affinity monolithic column and enzymatic chromogenic assay, the quantitation and detection limits of thrombin were as low as 5 nM and 2 nM, respectively. These results indicated that the GNPs attached monolith provided a novel technique to immobilize aptamers on an organic–inorganic hybrid monolith and it could be used to achieve highly selective recognition and determination of trace proteins.
Co-reporter:Jia-yuan Li;Xing-yu Long;He-xing Yin;Jun-qin Qiao
Journal of Separation Science 2016 Volume 39( Issue 13) pp:2562-2572
Publication Date(Web):
DOI:10.1002/jssc.201600231
Polydopamine-coated Fe3O4 magnetic nanoparticles synthesized through a facile solvothermal reaction and the self-polymerization of dopamine have been employed as a magnetic solid-phase extraction sorbent to enrich four phenolic compounds, bisphenol A, tetrabromobisphenol A, (S)-1,1′-bi-2-naphthol and 2,4,6-tribromophenol, from environmental waters followed by high-performance liquid chromatographic detection. Various parameters of the extraction were optimized, including the pH of the sample matrix, the amount of polydopamine-coated Fe3O4 sorbent, the adsorption time, the enrichment factor of analytes, the elution solvent, and the reusability of the nanoparticles sorbent. The recoveries of these phenols in spiked water samples were 62.0–112.0% with relative standard deviations of 0.8–7.7%, indicating the good reliability of the magnetic solid-phase extraction with high-performance liquid chromatography method. In addition, the extraction characteristics of the magnetic polydopamine-coated Fe3O4 nanoparticles were elucidated comprehensively. It is found that there are hydrophobic, π–π stacking and hydrogen bonding interactions between phenols and more dispersible polydopamine-coated Fe3O4 in water, among which hydrophobic interaction dominates the magnetic solid-phase extraction performance.
Co-reporter:Yan-hong Wang;Wen-jie Zhao;Wei-juan Zheng;Li Mao
Biological Trace Element Research 2016 Volume 170( Issue 1) pp:75-83
Publication Date(Web):2016 March
DOI:10.1007/s12011-015-0377-5
Intracellular metal elements exist in mammalian cells with the concentration range from picomoles per litre to micromoles per litre and play a considerable role in various biological procedures. Element provided by different species can influence the availability and distribution of the element in a cell and could lead to different biological effects on the cell’s growth and function. Zinc as an abundant and widely distributed essential trace element, is involved in numerous and relevant physiological functions. Zinc homeostasis in cells, which is regulated by metallothioneins, zinc transporter/SLC30A, Zrt-/Irt-like proteins/SLC39A and metal-response element-binding transcription factor-1 (MTF-1), is crucial for normal cellular functioning. In this study, we investigated the influences of different zinc species, zinc sulphate, zinc gluconate and bacitracin zinc, which represented inorganic, organic and biological zinc species, respectively, on cell cycle, viability and apoptosis in MDAMB231 cells. It was found that the responses of cell cycle, apoptosis and death to different zinc species in MDAMB231 cells are different. Western blot analysis of the expression of several key proteins in regulating zinc-related transcription, cell cycle, apoptosis, including MTF-1, cyclin B1, cyclin D1, caspase-8 and caspase-9 in treated cells further confirmed the observed results on cell level.
Co-reporter:Xing-yu Long, Qun Song and Hong-zhen Lian
Journal of Materials Chemistry A 2015 vol. 3(Issue 48) pp:9330-9339
Publication Date(Web):05 Nov 2015
DOI:10.1039/C5TB01378J
Lichee-like core–shell structured magnetic lutetium phosphate (Fe3O4@LuPO4) affinity microspheres were successfully synthesized and well characterized. Based on the properties of great specificity and rapid separation, magnetic LuPO4 microspheres were applied to selectively enrich phosphopeptides for MALDI-TOF MS analysis. The enrichment performance of the prepared microspheres was demonstrated by tryptic digests of standard protein (β-casein), complex samples (tryptic digest mixture of β-casein and bovine serum albumin at different molar ratios of 1:10 to 1:50), and real biological samples (fresh pure milk and human serum), respectively. The enrichment ability of magnetic LuPO4 microspheres for phosphopeptides was very satisfying and the captured phosphopeptides with a sharp enhancement in MS signals were reliably identified based on the appearance of metastable ion peaks with poor resolution of the corresponding dephosphorylated peptides in the mass spectra. Enrichment of phosphopeptides by the Fe3O4@LuPO4 affinity microspheres provides a powerful approach for large scale phosphoproteome analysis.
Co-reporter:Jing Yang;Jun-qin Qiao;Shi-hai Cui;Jia-yuan Li;Jin-jin Zhu;He-xing Yin;Cheng-yan Zhan
Journal of Separation Science 2015 Volume 38( Issue 11) pp:1969-1976
Publication Date(Web):
DOI:10.1002/jssc.201500167
Graphene-doped Fe3O4 nanocomposites were prepared by a solvothermal reaction of an iron source with graphene. The nanocomposites were characterized by transmission electron microscopy, atomic force microscopy, X-ray diffraction, superconducting quantum interference, Raman spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. This nanomaterial has been used as a magnetic solid-phase extraction sorbent to extract trace brominated flame retardants from environmental waters. Various extraction parameters were optimized including dosage and reusability of the nanocomposites, and pH of sample matrix. The reliability of the magnetic solid-phase extraction protocol based on graphene-doped Fe3O4 nanocomposites was evaluated by investigating the recoveries of 2,4,6-tribromophenol, tetrabromobisphenol A, 4-bromodiphenyl ether, and 4,4ʹ-dibromodiphenyl ether in water samples. Good recoveries (85.0–105.0%) were achieved with the relative standard deviation ranging from 1.1–7.1%. Moreover, it is speculated from characterization and magnetic solid-phase extraction experiment that there is not only π–π stacking but also possible hydrophobic interaction between the graphene-doped Fe3O4 nanocomposites and analytes.
Co-reporter:Peng Li;Li-min Li;Jing Xia;Shuai Cao;Xin Hu;Shen Ji
Journal of Separation Science 2015 Volume 38( Issue 23) pp:4043-4047
Publication Date(Web):
DOI:10.1002/jssc.201500814
An analytical method that combined high-performance liquid chromatography with inductively coupled plasma mass spectrometry has been developed for the determination of hexavalent chromium in traditional Chinese medicines. Hexavalent chromium was extracted using the alkaline solution. The parameters such as the concentration of alkaline and the extraction temperature have been optimized to minimize the interconversion between trivalent chromium and hexavalent chromium. The extracted hexavalent chromium was separated on a weak anion exchange column in isocratic mode, followed by inductively coupled plasma mass spectrometry determination. To obtain a better chromatographic resolution and sensitivity, 75 mM NH4NO3 at pH 7 was selected as the mobile phase. The linearity of the proposed method was investigated in the range of 0.2–5.0 μg L−1 (r2 = 0.9999) for hexavalent chromium. The limits of detection and quantitation are 0.1 and 0.3 μg L−1, respectively. The developed method was successfully applied to the determination of hexavalent chromium in Chloriti lapis and Lumbricus with satisfactory recoveries of 95.8–112.8%.
Co-reporter:Qun Song, Wen-jie Zhao, He-xing Yin and Hong-zhen Lian
RSC Advances 2015 vol. 5(Issue 78) pp:63896-63902
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5RA05872D
In this work, novel FeIII–tannic acid (TA) film-functionalized magnetic silica microspheres (designated Fe3O4@SiO2@FTA) were prepared via a facile deposition of one-step assembled FeIII–TA films on the surface of magnetic silica microspheres. The resulting Fe3O4@SiO2@FTA microspheres possessed strong magnetic responsiveness and good dispersity in aqueous solutions. We introduced low concentrations of standard peptide, standard protein, peptides in BSA tryptic digests and human urine to investigate the enrichment capability of the prepared nanocomposites. The enrichment process was very fast (only 5 min) and the peptide/protein–magnetic microsphere conjugates were readily separated by an external magnet. Moreover, the obtained conjugates can be directly analyzed by MALDI-TOF MS without any elution procedure. The enrichment performance was quite satisfying, indicating Fe3O4@SiO2@FTA microspheres as a universally applicable material for efficient and fast enrichment of peptides and proteins.
Co-reporter:Shu-ying Han, Chao Liang, Hui-min Yu, Jun-qin Qiao, Xin Ge and Hong-zhen Lian
RSC Advances 2015 vol. 5(Issue 36) pp:28840-28847
Publication Date(Web):17 Mar 2015
DOI:10.1039/C5RA02326B
The influence of n-octanol additive agent on the retention behavior, the uniformity of the retention mechanism, as well as the quantitative structure–retention relationships (QSRRs) of weak acidic and basic compounds on reversed-phase high performance liquid chromatography (RP-HPLC) was systematically discussed in this paper, especially for the QSRRs of logarithm of apparent n-octanol/water partition coefficient (logK′′ow) and logarithm of retention factor extrapolated to neat aqueous mobile phase (logkw(o)), which have not been discussed in other studies to date. For this purpose, the aqueous fraction of mobile phase was saturated with n-octanol and 0.25% (v/v) n-octanol was added into organic modifier. Eleven substituted benzoic acids, as well as fifteen anilines or pyridines were selected to establish QSRR models by using different types of ion-suppressors. The results indicated that the roles of n-octanol were different in various systems. For acids compounds, if perchloric acid (strong acid) acts as an ion-pair agent, the silanophilic interaction between solutes and residual silanol groups of alkyl-silica stationary phase can be ignored, and n-octanol/water partition and chromatographic process are homo-energetic. In this case, n-octanol acts only as organic modifier. However, if acetic acid (weak acid) or phosphoric acid/potassium dihydrogen phosphate (buffer salt) were used as the ion-suppressor, n-octanol is not only an organic modifier, but also a masking agent of free silanols. For weak bases, if ammonium chloride–ammonia was employed as the ion-suppressor, the addition of n-octanol will make QSRRs correlation significantly worse. Therefore, for studying on QSRRs of lipophilicity and retention behavior of acidic and basic compounds, n-octanol is only recommended for acidic system, and strong monoprotic acids, e.g., perchloric acid, are recommended as the ion-suppressors.
Co-reporter:Jun-qin Qiao;Dan Xu;Xin Ge
Research on Chemical Intermediates 2015 Volume 41( Issue 2) pp:691-703
Publication Date(Web):2015 February
DOI:10.1007/s11164-013-1221-1
A high performance liquid chromatography with ultraviolet detection was proposed for the separation and determination of relative substances in industrial arbutin and its synthetical intermediates 4-acetoxyphenol (ATP) and arbutin pentaacetate (ABPA). Liquid chromatography–mass spectrometry was used for further confirmation of these relative substances. As relative impurities, hydroquione (HQ) and 1,4-diacetoxybenzene (DATB) in industrial ATP, HQ, ATP, and DATB in industrial ABPA, and HQ, ATP, DATB, and ABPA in industrial arbutin were, respectively, quantified. As the results showed, the linearity of standard curves was excellent with relative coefficients of over 0.999 for all the detected components, and the intra- and inter-day precisions of impurities determination were satisfactory, with relative standard deviations of not more than 4.0 %. The distribution and transfer of related substances were elucidated in the synthesis process of arbutin. The established HPLC method not only has great potential in quality control of arbutin but can also be used to instruct the optimization of the synthesis procedure.
Co-reporter:Chao Liang, Hong-zhen Lian
TrAC Trends in Analytical Chemistry 2015 Volume 68() pp:28-36
Publication Date(Web):May 2015
DOI:10.1016/j.trac.2015.02.009
•Lipophilicity measurement by reversed-phase high-performance liquid chromatography.•We evaluate the theoretical basis of lipophilicity.•We pay special attention to lipophilicity determination of dissociable compounds.•We introduce novel mobile and stationary phases for lipophilicity measurement.Lipophilicity, quantified by the logarithm of the n-octanol/water partition coefficient (logP) or the distribution coefficient (logD), is a crucial parameter for modelling biological partition or distribution. As a maintream experimental method for lipophilicity measurement, reversed-phase high performance liquid chromatography (RP-HPLC) has attracted great interest and the attention of researchers throughout the world for its advantages including speed, reproducibility, insensitivity to impurities and degradation products, broad dynamic range, on-line detection, and reduced handling and sizes of samples. This review focuses on recent developments in lipophilicity measurement by RP-HPLC, both theoretical and experimental (mainly mobile and stationary phases).
Co-reporter:Zheng Wang, Jin-cheng Zhao, Hong-zhen Lian, Hong-yuan Chen
Talanta 2015 Volume 138() pp:52-58
Publication Date(Web):1 June 2015
DOI:10.1016/j.talanta.2015.02.009
•We immobilize aptamer on hybrid monolithic column by facile thiol-ene click reaction.•The coverage density of aptamer of thrombin on the monolith is high to 420 pmol μL−1.•The affinity monolithic column retains thrombin with high specificity and capacity.•We assay thrombin extracted by the affinity column using chromogenic substrate T1637.A novel strategy for preparing aptamer-based organic-silica hybrid monolithic column was developed via “thiol-ene” click chemistry. Due to the large specific surface area of the hybrid matrix and the simplicity, rapidness and high efficiency of “thiol-ene” click reaction, the average coverage density of aptamer on the organic-silica hybrid monolith reached 420 pmol μL−1. Human α-thrombin can be captured on the prepared affinity monolithic column with high specificity and eluted by NaClO4 solution. N-p-tosyl-Gly-Pro-Arg p-nitroanilide acetate was used as the sensitive chromogenic substrate of thrombin. The thrombin enriched by this affinity column was detected with a detection of limit of 0.01 μM by spectrophotometry. Furthermore, the extraction recovery of thrombin at 0.15 μM in human serum was 91.8% with a relative standard deviation of 4.0%. These results indicated that “thiol-ene” click chemistry provided a promising technique to immobilize aptamer on organic–inorganic hybrid monolith and the easily-assembled affinity monolithic material could be used to realize highly selective recognition of trace proteins.
Co-reporter:Peng Li, Yi-jun Chen, Xin Hu, Hong-zhen Lian
Talanta 2015 Volume 134() pp:292-297
Publication Date(Web):1 March 2015
DOI:10.1016/j.talanta.2014.11.026
•Magnetic SPE combined with ICP-MS was developed for speciation of trace antimony.•C8-Fe3O4@SiO2 nanoparticle was prepared and used as magnetic SPE adsorbent.•APDC was used as the additive to form hydrophobic complexes with Sb species.•Separation and perconcentration of Sb(III) and Sb(V) was achieved by adjusting pH.A new magnetic solid phase extraction (MSPE) method using octyl-immobilized silica-coated magnetic Fe3O4 (C8-Fe3O4@SiO2) nanoparticles as the MSPE adsorbent combined with inductively coupled plasma mass spectrometry (ICP-MS) has been developed for speciation analysis of Sb(III) and Sb(V). At pH 5.0, Sb(III) forms a hydrophobic complex with ammonium pyrrolidine dithiocarbamate (APDC) and is retained on C8-Fe3O4@SiO2 nanoparticles, whereas Sb(V) remains as free species in aqueous solution. At pH 2.0, both Sb species (total Sb) form hydrophobic APDC complexes, being retained on the adsorbent. Thus, sensitive speciation analysis of Sb(III) and Sb(V) could be achieved by selective SPE of either Sb(III) or total Sb under different pH on C8-Fe3O4@SiO2 nanoparticles. The experimental parameters, such as pH of solution, concentration of APDC, eluent type and sample volume were optimized in detail. The limits of detection (LOD, 3δ, n=10) of this MSPE method was 0.001 μg L−1 and 0.004 μg L−1, respectively, for Sb(III) and Sb(V). The precision of the method (Relative standard deviation, RSD, n=6) for Sb(III) and Sb(V) at 1.0 μg L−1 was 3.4% and 4.6%, respectively. In order to verify the accuracy of the method, certified reference material (GSB 07-1376-2001) of environmental water was analyzed and the result obtained was in good agreement with the certified values. This proposed method is simple, accurate and sensitive, and can be applied to the speciation of Sb(III) and Sb(V) in environmental waters without any pre-reduction or pre-oxidation operation.
Co-reporter:Jing Yang, Jia-yuan Li, Jun-qin Qiao, Hong-zhen Lian, Hong-yuan Chen
Journal of Chromatography A 2014 Volume 1325() pp:8-15
Publication Date(Web):17 January 2014
DOI:10.1016/j.chroma.2013.11.052
•The mechanism that Fe3O4/C nanoparticles extract PAHs and other analysts is studied.•Adsorption/desorption property of Fe3O4/C is compared with that of activated carbon.•Fe3O4/C is used as chromatographic stationary phase for its retention elucidation.•Hydrophobic interaction plays the dominant role in MSPE process of PAHs by Fe3O4/C.•Hydrogen bonding/dipole–dipole attraction participates in the MSPE of other analytes.Carbon decorated Fe3O4 nanoparticles (Fe3O4/C) are promising magnetic solid-phase extraction (MSPE) sorbents in environmental and biological analysis. Fe3O4/C based MSPE method shows advantages of easy operation, rapidness, high sensitivity, and environmental friendliness. In this paper, the MSPE mechanism of Fe3O4/C nanoparticles has been comprehensively investigated, for the first time, through the following three efforts: (1) the comparison of extraction efficiency for polycyclic aromatic hydrocarbons (PAHs) between the Fe3O4/C sorbents and activated carbon; (2) the chromatographic retention behaviors of hydrophobic and hydrophilic compounds on Fe3O4/C nanoparticles as stationary phase; (3) related MSPE experiments for several typical compounds such as pyrene, naphthalene, benzene, phenol, resorcinol, anisole and thioanisole. It can be concluded that there are hybrid hydrophobic interaction and hydrogen bonding interaction or dipole–dipole attraction between Fe3O4/C sorbents and analytes. It is the existence of carbon and oxygen-containing functional groups coated on the surface of Fe3O4/C nanoparticles that is responsible for the effective extraction process.
Co-reporter:Peng Li, Xiao-qin Zhang, Yi-jun Chen, Tian-yi Bai, Hong-zhen Lian and Xin Hu
RSC Advances 2014 vol. 4(Issue 90) pp:49421-49428
Publication Date(Web):19 Sep 2014
DOI:10.1039/C4RA06563H
A series of thiol- and amine-bifunctionalized mesoporous silicas were synthesized via one-pot co-condensation of tetraethylorthosilicate, 3-mercaptopropyltrimethoxysilane and N-(2-aminoethyl)-3-aminopropyltriethoxysilane. The mesoporous materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen gas adsorption, infrared spectroscopy, thermogravimetric analysis and elemental analysis. As(V) and As(III) were effectively adsorbed by amine and thiol on the functionalized silica, respectively, through electrostatic interaction and chelation. Adsorption isotherms and kinetic uptake profiles of As(V) and As(III) onto these adsorbents were investigated by batch adsorption experiments. Moreover, this material was employed for the speciation analysis of arsenic using a home-made syringe-based solid phase extraction device. As(V) and As(III) were effectively separated and pre-concentrated in a single run through a sequential elution strategy, in which 0.1 M HNO3 was first used to selectively elute As(V), and then 1 M HNO3 with 0.01 M KIO3 was used to elute As(III). The merits of easy preparation, low cost, high adsorption capacity and selective desorption make the bifunctional mesoporous silica an ideal solid material for the removal and speciation analysis of arsenic in environmental waters.
Co-reporter:Jing Yang, Jia-yuan Li, Jun-qin Qiao, Shi-hai Cui, Hong-zhen Lian, Hong-yuan Chen
Applied Surface Science 2014 Volume 321() pp:126-135
Publication Date(Web):1 December 2014
DOI:10.1016/j.apsusc.2014.09.175
Highlights
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Magnetic Fe3O4/C nanospheres were used in MSPE of BFRs and PCP from water samples.
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The method shows merits of simpleness, reliableness and environmental friendliness.
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The bonding between Fe3O4 and coated organic carbon has been demonstrated in Fe3O4/C.
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The straight influences of synthesis conditions of Fe3O4/C on MSPE were investigated.
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The extraction characteristics of Fe3O4/C nanoparticles were further elucidated.
Co-reporter:Peng Li, Yi-jun Chen, Hong-zhen Lian and Xin Hu
Journal of Analytical Atomic Spectrometry 2014 vol. 29(Issue 10) pp:1785-1790
Publication Date(Web):14 Jul 2014
DOI:10.1039/C4JA00149D
In this work, a centrifugal microfluidic platform with multiple solid phase extraction (SPE) units has been developed and successfully applied to separate Cr(VI) and Cr(III) with high throughput, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Monolithic capillary columns, prepared by polymerization of N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AEAPTES) and tetraethoxysilane (TEOS), were integrated on a PDMS chip and used as the media for the selective extraction of Cr(VI). The aqueous solutions on the chip were driven by the centrifugal force produced by a centrifugal motor, so that high-throughput SPE is achieved by processing multiple samples simultaneously. The adsorption and elution conditions of Cr(VI) onto the monolithic capillary column, and the rotation speed of the centrifugal motor were well studied. The feasibility of the proposed protocol was validated by certified reference materials and real water samples. In contrast to the traditional speciation analysis procedure, the species separation of eight samples can be finished within 10 min on the established centrifugal microfluidic platform. This device possessing the advantages of portability and simplicity provides a potential application for field sampling and pretreatment.
Co-reporter:Chao Liang;Shu-ying Han;Jun-qin Qiao;Xin Ge
Journal of Separation Science 2014 Volume 37( Issue 22) pp:3226-3234
Publication Date(Web):
DOI:10.1002/jssc.201400681
A strategy to utilize neutral model compounds for lipophilicity measurement of ionizable basic compounds by reversed-phase high-performance liquid chromatography is proposed in this paper. The applicability of the novel protocol was justified by theoretical derivation. Meanwhile, the linear relationships between logarithm of apparent n-octanol/water partition coefficients (logKow′′) and logarithm of retention factors corresponding to the 100% aqueous fraction of mobile phase (logkw) were established for a basic training set, a neutral training set and a mixed training set of these two. As proved in theory, the good linearity and external validation results indicated that the logKow′′–logkw relationships obtained from a neutral model training set were always reliable regardless of mobile phase pH. Afterwards, the above relationships were adopted to determine the logKow of harmaline, a weakly dissociable alkaloid. As far as we know, this is the first report on experimental logKow data for harmaline (logKow = 2.28 ± 0.08). Introducing neutral compounds into a basic model training set or using neutral model compounds alone is recommended to measure the lipophilicity of weakly ionizable basic compounds especially those with high hydrophobicity for the advantages of more suitable model compound choices and convenient mobile phase pH control.
Co-reporter:Peng Li, Xiao-qin Zhang, Yi-jun Chen, Hong-zhen Lian and Xin Hu
Analytical Methods 2014 vol. 6(Issue 12) pp:4205-4211
Publication Date(Web):10 Apr 2014
DOI:10.1039/C4AY00438H
A sequential solid phase microextraction (SPME) system consisting of two monolithic capillary columns was developed for simultaneous separation and preconcentration of inorganic arsenic, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AEAPTES) incorporated organic–inorganic hybrid monolithic column was prepared in situ by sol–gel technology in a fused capillary and employed as the extraction medium for SPME in this system, because the amino active sites on the synthesized monolith possess a high adsorption selectivity for As(V). With the on-line design of dual columns and an oxidation coil, As(V) is quantitatively extracted by the first column, and As(III) in the effluent can be quantitatively extracted by the second column after oxidization to As(V) by a make-up KMnO4 solution. The retained As(V) or As(III) is then sequentially eluted by diluted HNO3 and introduced to ICP-MS for determination. In this work, the parameters effecting the retention and elution of As(V) and As(III) were optimized in detail. On-line SPME of 1 mL sample solution gave a signal enhancement factor of 60 for both As(V) and As(III) using the system. The precision (RSD) for six replicate measurements of 1 μg L−1 As(V) and As(III) were 3.8% and 3.2%, respectively. The limits of detection (LODs, defined as three times the signal-to-noise ratio) for As(V) and As(III) were 0.005 μg L−1. The developed method was successfully applied to the speciation analysis of inorganic arsenic in drinking and environmental waters with satisfactory recoveries.
Co-reporter:Jing Yang, Shihai Cui, Jun-qin Qiao, Hong-zhen Lian
Journal of Molecular Catalysis A: Chemical 2014 Volume 395() pp:42-51
Publication Date(Web):December 2014
DOI:10.1016/j.molcata.2014.08.001
•Co doped TiO2 nanoparticle was used as photocatalyst for halophenols degradation.•It is the first time to compare the degradation rate between CPs and BPs on TiO2/Co.•The degradation of both CPs and BPs obeys the pseudo-first-order kinetics.•BPs are easier to be photodegradated than CPs by TiO2/Co nano catalyst.•The degradation of 2,4,6-TCP and 2,4,6-TBP occurs via the dehalogenation pathway.Cobalt doped TiO2 nanoparticle prepared by ultrasonic-assisted hydrothermal method was used as the photocatalyst in the degradation of chlorophenols (CPs) and bromophenols (BPs). The doping content of cobalt in this catalyst was optimized as 0.5 wt%. The degradation rates of 2,4,6-trichlorophenol (2,4,6-TCP), 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP), 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4,6-tribromophenol (2,4,6-TBP), 2,4-dibromophenol (2,4-DBP), 2,6-dibromophenol (2,6-DBP), 2-bromophenol (2-BP) and 4-bromophenol (4-BP) were estimated based on the quantitative determination of the degradation products. It was found that the degradation of CPs and BPs underwent dehalogenation process with pseudo-first-order kinetics. Moreover, the photodegradation kinetics was compared between CPs and BPs. The degradation rate of BPs was more quickly than CPs due to the difference in bond energy of carbon–halogen, and the degradation rates of BPs and CPs were mainly dependent on the number and the position of substituting halogen atom respectively. In addition, 2,4,6-TCP and 2,4,6-TBP can be effectively degraded by more than 95.1% and 93.5%, respectively, within 240 and 30 min. Tri-substituted phenols were firstly photodegraded to corresponding di-substituted ones, then to mono-substituted ones, and finally to phenol by TiO2/Co nano catalyst, although there were some differences in selectivity, rate and yield in the dehalogenation pathway of 2,4,6-TCP and 2,4,6-TBP.
Co-reporter:Ting-ting Yang, Lin-feng Zhou, Jun-qin Qiao, Hong-zhen Lian, Xin Ge, Hong-yuan Chen
Journal of Chromatography A 2013 Volume 1291() pp:1-9
Publication Date(Web):24 May 2013
DOI:10.1016/j.chroma.2013.03.043
•A poly(MATE-co-EGDMA) monolith is prepared as PMME medium for BFRs.•The PMME-HPLC system can be used to extract and determine three representative BFRs.•The analytical results for environmental water samples are satisfactory.•On-monolith retention mechanism is investigated as well.A capillary poly(trimethyl-2-methacroyloxyethylammonium chloride-co-ethylene glycol dimethacrylate) monolith was in situ synthesized by thermally initiated free radical co-polymerization using trimethyl-2-methacroyloxyethylammonium chloride (MATE) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. N,N-dimethylformamide and polyethylene glycol 6000 were used as solvent and porogen, respectively. The morphology and porous structure of the resulting monoliths were assessed by scanning electron microscope. In order to prepare practically useful poly(MATE-co-EGDMA) monoliths with low flow resistance and good mechanical strength, some parameters such as PEG-6000 to DMF ratio, total monomer to porogen ratio, and crosslinker to monomer ratio were optimized systematically. Moreover, the extraction mechanism was evaluated using two series of compounds, alkylbenzenes and weak acids, as model compounds on poly(MATE-co-EGDMA) monoliths as liquid chromatographic stationary phase. Finally, the monoliths were applied as the solid phase microextraction medium, and a simple off-line method for simultaneous determination of three brominated flame retardants, 2,4,6-tribromophenol (TBP), tetrabromobisphenol A (TBBPA) and 4,4′-dibrominated diphenyl ether (DBDPE), in environmental waters was developed by coupling the polymer monolith microextraction to HPLC with UV detection. The regression equations for these three brominated flame retardants showed good linearity from their limit of quantification to 5000 ng/mL. The limits of detection were 0.20, 0.15 and 0.10 ng/mL for TBP, TBBPA and DBDPE, respectively. The recovery of the proposed method was 78.7–106.1% with intra-day relative standard deviation of 1.3–4.4%.
Co-reporter:Jin Zhang;Wen-Wen Liu;Jun-Qin Qiao
Research on Chemical Intermediates 2013 Volume 39( Issue 5) pp:2035-2041
Publication Date(Web):2013 May
DOI:10.1007/s11164-012-0734-3
An ion suppression reversed phase high performance liquid chromatography method has been developed for the determination of 2,6-di-tert-butylphenol in Irganox 1425. Separation was carried out on a Welch Material Ultimate XB-C18 column (5 μm, 150 mm × 4.6 mm), using methanol–water (0.1 % HClO4) (75/25, v/v) mixture as the mobile phase in an isocratic elution. Detection was performed by UV absorption at a wavelength of 275 nm, and the limit of detection was 0.2 μg/mL. The method presented excellent repeatability and precision with both intra- and inter-day relative standard deviations (RSDs) of less than 2.0 %, as well as satisfactory accuracy with the recovery of 98.7–102.3 %, and therefore can be applied for the quality control analysis of Irganox 1425 industrial product.
Co-reporter:Xiao-wen Cao;Wei-jian Shen;Jie Zhu;Jin Zhang;Yuan Jiang
Food Analytical Methods 2013 Volume 6( Issue 2) pp:445-456
Publication Date(Web):2013 April
DOI:10.1007/s12161-012-9447-x
A gas chromatography–mass spectrometry (GC–MS) multi-residue method with different ionization modes has been developed for the determination of 23 organochlorine pesticides and ten polychlorinated biphenyls (PCBs) in crayfish. The approach was based on an extraction with acetonitrile saturated by hexane (containing 0.1 % acetic acid), followed by a dispersed solid-phase extraction cleanup with primary secondary amine and octadecylsilane, and finally analyzed by GC–MS/MS operated in electron impact (EI) and positive chemical ionization (PCI), and GC–MS in negative chemical ionization (NCI), respectively. An isotope internal standard, DDT-D8, was used for quantification. These three GC–MS procedures were validated and compared using crayfish samples fortified at three levels (5, 10 and 20 ng/g). Good linearity, accuracy, precision and sensitivity were achieved by all three ionization modes with recoveries in the range of 70 to 112 %, relative standard deviations (RSDs) below 10 % and limits of detection (LODs) in the range of 0.002 to 8 ng/g. Extremely high selectivity was obtained by both EI- and PCI-MS/MS, while PCI was more sensitive to compounds containing nitro and carbonyl groups, and EI was a better choice for dieldrin, endosulfan, and its metabolites. NCI-MS had the highest sensitivity but lower anti-interference ability and was not suitable for the determination of DDTs and PCBs. These three ionization modes can be used as complementary and alternative in routine GC–MS analysis of organochlorine pesticides and polychlorinated biphenyls in food.
Co-reporter:Yan-hong Wang;Ke-jin Li;Li Mao;Xin Hu;Wen-jie Zhao
Biological Trace Element Research 2013 Volume 154( Issue 3) pp:418-426
Publication Date(Web):2013 September
DOI:10.1007/s12011-013-9737-1
As a non-toxic metal to humans, zinc is essential for cell proliferation, differentiation, regulation of DNA synthesis, genomic stability and mitosis. Zinc homeostasis in cells, which is crucial for normal cellular functioning, is maintained by various protein families including ZnT (zinc transporter/SLC30A) and ZIP (Zrt-, Irt-like proteins/SLC39A) that decrease and increase cytosolic zinc availability, respectively. In this study, we investigated the influences of a specific concentration range of ZnSO4 on cell cycle and apoptosis by flow cytometry, and cell viability by MTT method in MDAMB231, HepG2 and 293 T cell lines. Fluorescent sensors NBD-TPEA and the counterstain for nuclei Hoechst 33342 were used to stain the treated cells for observing the localisation and amount of Zn2+ via laser scanning confocal microscope. It was found that the influence manners of ZnSO4 on cell cycle, apoptosis and cell viability in various cell lines were different and corresponding to the changes of Zn2+ content of the three cell lines, respectively. The significant increase on intracelluar zinc content of MDAMB231 cells resulted in cell death, G1 and G2/M cell cycle arrest and increased apoptotic fraction. Additionally, the mRNA expression levels of ZnT and ZIP families in the three cell lines, when treated with high concentration of ZnSO4, increased and decreased corresponding to their functions, respectively.
Co-reporter:Hong-mei Jiang, Ting Yang, Yan-hong Wang, Hong-zhen Lian, Xin Hu
Talanta 2013 Volume 116() pp:361-367
Publication Date(Web):15 November 2013
DOI:10.1016/j.talanta.2013.05.008
•We proposed a magnetic SPE method for the speciation of Cr(III) and Cr(VI).•We evaluated the impacts of MSPE parameters and speciation procedure.•We investigated adsorption mechanism of Cr(III) and Cr(VI) on adsorbent.A new approach of magnetic solid phase extraction (MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) has been developed for the speciation of Cr(III) and Cr(VI) using zincon-immobilized silica-coated magnetic Fe3O4 nanoparticles (Zincon–Si–MNPs) as the MSPE absorbent. Cr(III) was quantitatively reserved on the absorbent at pH 9.1 while total Cr was reserved at pH 6.5. The absorbed Cr species were eluted by using 2 mol/L HCl and detected by GFAAS. The concentration of Cr(VI) could be calculated by subtracting Cr(III) from total Cr. All the parameters affecting the separation and extraction efficiency of Cr species such as pH, extraction time, concentration and volume of eluent, sample volume and influence of co-existing ions were systematically examined and the optimized conditions were established accordingly. The detection limit (LOD) of the method was 0.016 and 0.011 ng mL−1 for Cr(III) and Cr(VI), respectively, with the enrichment factor of 100 and 150. The precisions of this method (Relative standard deviation, RSD, n=7) for Cr(III) and Cr(VI) at 0.1 ng mL−1 were 6.0% and 6.2%, respectively. In order to validate the proposed method, a certified reference material of environmental water was analyzed, and the result of Cr speciation was in good agreement with the certified value. This MSPE–GFAAS method has been successfully applied for the speciation of Cr(III) and Cr(VI) in lake and tap waters with the recoveries of 88–109% for the spiked samples. Moreover, the MSPE separation mechanism of Cr(III) and Cr(VI) based on their adsorption–desorption on Zincon–Si–MNPs has been explained through various spectroscopic characterization.
Co-reporter:Wen-Sheng Zou, Jing Yang, Ting-Ting Yang, Xin Hu and Hong-Zhen Lian
Journal of Materials Chemistry A 2012 vol. 22(Issue 11) pp:4720-4727
Publication Date(Web):26 Jan 2012
DOI:10.1039/C2JM15139A
In recent decades, considerable efforts related to the study of 2,4,6-trinitrotoluene (TNT) have been focused on either developing ultraselective and ultrasensitive methods for real-time analytical detection or exploiting highly efficient and green technologies for treatment of contaminated waters. In the present work, combining the magnetic response property of Fe3O4 nanoparticles with the chemosensory property of quantum dots (QDs), Fe3O4 magnetic nanoparticles and Mn-doped ZnS QD nanocomposites (MNPs/QD NCs) have been synthesized and used for room-temperature phosphorescence (RTP) sensing and magnetic separation of captured ultratrace TNT in water. Notably, magnetic-RTP MNPs/QD NCs were found as photo-driven enzyme mimetics for degradation of TNT through Haber–Weiss cycle reactions for the first time. Meanwhile, MNPs/QD NCs exhibited a highly selective response for TNT with detection limit down to 12.5 nM through the quenching of 4T1–6A1 transition emission. By in situ monitoring electron paramagnetic resonance (EPR) signals, production of hydroxyl radical (OH˙) is attributed fundamentally to the catalytic reactions occurring at metal ions on the surface of Fe3O4 nanoparticles rather than those released from the MNPs into a solution. The proposed methods, as well as being suitable for detecting ultratrace TNT and distinguishing different nitro-compounds, could be used as one of the most promising approaches for developing highly efficient degradation of organics contaminated waters to generate treated waters which could be easily reused or released into the environment without any harmful effects.
Co-reporter:Shu-ying Han, Chao Liang, Jun-qin Qiao, Hong-zhen Lian, Xin Ge, Hong-yuan Chen
Analytica Chimica Acta 2012 Volume 713() pp:130-135
Publication Date(Web):3 February 2012
DOI:10.1016/j.aca.2011.11.020
The retention factor corresponding to pure water in reversed-phase high performance liquid chromatography (RP-HPLC), kw, was commonly obtained by extrapolation of retention factor (k) in a mixture of organic modifier and water as mobile phase in tedious experiments. In this paper, a relationship between log kw and log k for directly determining kw has been proposed for the first time. With a satisfactory validation, the approach was confirmed to enable easy and accurate evaluation of kw for compounds in question with similar structure to model compounds. Eight PCB congeners with different degree of chlorination were selected as a training set for modeling the log kw − log k correlation on both silica-based C8 and C18 stationary phases to evaluate log kw of sample compounds including seven PCB, six PBB and eight PBDE congeners. These eight model PCBs were subsequently combined with seven structure-similar benzene derivatives possessing reliable experimental Kow values as a whole training set for log Kow − log kw regressions on the two stationary phases. Consequently, the evaluated log kw values of sample compounds were used to determine their log Kow by the derived log Kow − log kw models. The log Kow values obtained by these evaluated log kw were well comparable with those obtained by experimental-extrapolated log kw, demonstrating that the proposed method for log kw evaluation in this present study could be an effective means in lipophilicity study of environmental contaminants with numerous congeners. As a result, log Kow data of many PCBs, PBBs and PBDEs could be offered. These contaminants are considered to widely exist in the environment, but there have been no reliable experimental Kow data available yet.Graphical abstractHighlights► A novel log kw evaluation protocol was proposed for the first time. ► The approach greatly simplified Kow measuring procedure for lipophilic compounds. ► Log Kow data of 21 PCBs, PBBs and PBDEs were determined for the first time.
Co-reporter:Lin-feng Zhou, Xu-gan He, Jun-qin Qiao, Hong-zhen Lian, Xin Ge, Hong-yuan Chen
Journal of Chromatography A 2012 Volume 1256() pp:15-21
Publication Date(Web):21 September 2012
DOI:10.1016/j.chroma.2012.07.047
A simple and facile needle-adapter was designed for constructing manual on-line polymer monolith microextraction-high performance liquid chromatography (PMME-HPLC). A capillary poly(4-vinylpyridine-co-ethylene glycol dimethacrylate) [poly(VP-co-EGDMA)] monolith was prepared by in situ polymerization, using 4-vinylpyridine (VP) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The synthesized monolith was used as the extraction medium for concentrating four EPA priority pollutants, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol, from water samples. The effect of the dosage of porogen polyethylene glycol 6000 (PEG) on back pressure and extraction performance of the capillary monolith was also investigated. Moreover, the influences of several parameters (such as extraction time, desorption time, content of MeOH in sample solution and sample pH) were examined to obtain the optimal PMME conditions. As a result, the established on-line PMME-HPLC protocol, with good extraction efficiency (80.6–91.7%), satisfactory recovery (94.7–106% and 76.8–86.3% for water and serum samples, respectively) and low detection limit (0.3–1.4 μg/L), exhibited potential applicability for the analysis of chlorophenols in environmental and biological samples.Highlights► Manual on-line PMME-HPLC system was constructed based on a facile needle-adapter. ► Poly(VP-co-EGDMA) monolith was prepared as a new PMME medium. ► The PMME-HPLC system can be used to extract and determine chlorophenols. ► Less sample consumption and shorter extraction time were needed for water and serum. ► Generally lower LODs relative to other off-line SPME-HPLC methods was another advantage.
Co-reporter:Shu-ying Han, Chao Liang, Kuan Zou, Jun-qin Qiao, Hong-zhen Lian, Xin Ge
Talanta 2012 Volume 101() pp:64-70
Publication Date(Web):15 November 2012
DOI:10.1016/j.talanta.2012.08.051
The variation in mobile phase pH and ionizable solute dissociation constant (pKa) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid–base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (Kow″) and the related quantitative structure–retention relationship (QSRR) of log Kow″ vs. log kw, the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for Kow measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pKa will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of log Kow″ vs. log kw were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor.Highlights► (Mobile phase pH—solute pKa) is independent of change of organic modifier fraction. ► The variation in pH and pKa does not affect QSRR of log Kow″ and log kw for weak acids. ► The rigorous pH and pKa measurement in relative studies is not compulsively necessary.
Co-reporter:Shu-ying Han, Jun-qin Qiao, Yun-yang Zhang, Hong-zhen Lian, Xin Ge
Talanta 2012 Volume 97() pp:355-361
Publication Date(Web):15 August 2012
DOI:10.1016/j.talanta.2012.04.045
The utilization of neutral compounds as model compounds is put forward for determination of the n-octanol/water partition coefficient (Kow) of highly hydrophobic, weak acidic compounds by reversed-phase high performance liquid chromatography (RP-HPLC). It is based on a linear relationship between the logarithm of apparent n-octanol/water partition coefficient (log Kow″), expressing hydrophobicity of acidic solutes more accurately, and the logarithm of RP-HPLC retention factor of the solutes corresponding to the neat aqueous fraction of mobile phase (log kw). The availability of neutral model compounds was theoretically tested for this novel protocol. Moreover, a high consistency of linear log Kow″–log kw correlations was demonstrated between a mixed training set of neutral and acidic model compounds, and a training set of neutral model compounds. It is proved in theory that for a certain set of compounds investigated, all derived linear relationships between log Kow″ and log kw have a unit slope and the same intercept, regardless of mobile phase pH. This model was applied to measure log Kow of lipophilic aristolochic acid I (AA I) and aristolochic acid II (AA II). Log Kow values for AA I and AA II are 4.45±0.07 and 3.99±0.06, respectively. To the best of our knowledge, this is the first report on experimental log Kow data for AAs. The proposed strategy solves the problem of lacking suitable acidic model compounds with reliable experimental Kow in determining Kow of lipophilic acidic solutes by RP-HPLC.Highlights► Feasibility of neutral model compounds was studied for modified Collander equation. ► A unit slope with invariant intercept was theoretically proved in Collander equation. ► Experimental log Kow of aristolochic acids I and II were first reported.
Co-reporter:Hong-mei Jiang, Zhong-peng Yan, Yue Zhao, Xin Hu, Hong-zhen Lian
Talanta 2012 Volume 94() pp:251-256
Publication Date(Web):30 May 2012
DOI:10.1016/j.talanta.2012.03.035
A new protocol using zincon-immobilized silica-coated magnetic Fe3O4 nanoparticles (Zincon–Si–MNPs) as solid-phase extraction (SPE) medium has been developed for the separation and preconcentration of trace lead in water. Various parameters such as pH, extraction time, concentration and volume of eluent, sample volume, and influence of co-existing ions have been investigated in order to establish the optimum conditions for the determination of lead in combination with graphite furnace atomic absorption spectrometry (GFAAS). The detection limit (LOD) of the proposed method for lead based on an enrichment factor of 200 was 10 ng L−1. The relative standard deviations (RSDs, n = 5) were 8.3%, 7.8% and 9.2%, respectively, at 5, 0.5 and 0.05 ng mL−1 levels. This method has been successfully applied to the analysis of trace lead in natural and drinking water samples and the recoveries for the spiked samples were in the range of 84–104%.Highlights► We synthesize a novel magnetic nanometer-sized SPE material Zincon–Si–MNPs. ► The adsorbent is characterized by IR, TEM and XRD. ► The new adsorbent shows high enrichment factor for lead in short analytical time. ► We propose a magnetic SPE method for the determination of trace lead in waters. ► The magnetic SPE procedure is very easy to operate.
Co-reporter:Wen-Sheng Zou, Dong Sheng, Xin Ge, Jun-Qin Qiao, and Hong-Zhen Lian
Analytical Chemistry 2011 Volume 83(Issue 1) pp:30
Publication Date(Web):November 30, 2010
DOI:10.1021/ac1008942
Rayleigh scattering (RS) as an interference factor to detection sensitivity in ordinary fluorescence spectrometry is always avoided in spite of considerable efforts toward the development of RS-based resonance Rayleigh scattering (RRS) and hyper-Rayleigh scattering (HRS) techniques. Here, combining advantages of quantum dots (QDs) including chemical modification of functional groups and the installation of recognition receptors at their surfaces with those of phosphorescence such as the avoidance of autofluorescence and scattering light, l-cys-capped Mn-doped ZnS QDs have been synthesized and used for room-temperature phosphorescence (RTP) to sense and for RS chemodosimetry to image ultratrace 2,4,6-trinitrotoluene (TNT) in water. The l-cys-capped Mn-doped ZnS QDs interdots aggregate with TNT species induced by the formation of Meisenheimer complexes (MHCs) through acid−base pairing interaction between l-cys and TNT, hydrogen bonding, and electrostatic interaction between l-cys intermolecules. Although the resultant MHCs may quench the fluorescence at 430 nm, interdots aggregation can greatly influence the light scattering property of the aqueous QDs system, and therefore, dominant RS enhancement at defect-related emission wavelength was observed under the excitation of violet light of Mn-doped ZnS QDs, which was applied in chemodosimetry to image TNT in water. Meanwhile, Mn-doped ZnS QDs also exhibited a highly selective response to the quenching of the 4T1−6A1 transition emission (RTP) and showed a very good linearity in the range of 0.0025−0.45 μM TNT with detection limit down to 0.8 nM and RSD of 2.3% (n = 5). The proposed methods are well-suited for detecting the ultratrace TNT and distinguishing different nitro compounds.
Co-reporter:Wen-sheng Zou, Jun-qin Qiao, Xin Hu, Xin Ge, Hong-zhen Lian
Analytica Chimica Acta 2011 Volume 708(1–2) pp:134-140
Publication Date(Web):5 December 2011
DOI:10.1016/j.aca.2011.09.044
In this paper, cobalt (Co2+)-doped (CoD) ZnS quantum dots (QDs) are synthesised in aqueous solution and characterised for the first time. l-Cysteine (l-Cys) ligands on the surface of CoD ZnS QDs can bind 2,4,6-trinitrotoluene (TNT) to form Meisenheimer complexes (MHCs) mainly through acid–base pairing interactions between TNT and l-Cys and the assistance of hydrogen bonding and electrostatic co-interactions among l-Cys intermolecules. The aggregation of inter-dots induced by MHCs greatly influenced the light scattering property of the QDs in aqueous solution, and Rayleigh scattering (RS) enhancement at the defect-related emission wavelengths as well as its left side was observed with the excitation of CoD ZnS QDs by violet light. RS enhancement, combining with the quenching of the orange transition emission induced by TNT anions, resulted in a change in the ratiometric visualisation of the system being investigated. A novel CoD ZnS QD-based hybrid ratiometric chemosensor has therefore been developed for simple and sensitive analysis of TNT in water. This ratiometric probe can assay down to 25 nM TNT in solution without interference from a matrix of real water sample and other nitroaromatic compounds. Because of the excellent electron-accepting ability and strong affinity of TNT to l-Cys on the surface of CoD ZnS QDs, the CoD photoluminescent nanomaterials reported here are well suited for detecting ultra-trace TNT and for distinguishing different nitro-compounds in aqueous solution.Graphical abstractHighlights► CoD ZnS QDs were synthesised in aqueous solution and characterised. ► Phosphorescence lifetime of the synthesised CoD ZnS QDs was 3.0 ms. ► CoD ZnS QDs has great potential as a hybrid colorimetric assay for sensing TNT. ► This colorimetric probe can detect down to 25 nM TNT.
Co-reporter:Chong-yu Shen, Xiao-wen Cao, Wei-jian Shen, Yuan Jiang, Zeng-yun Zhao, Bin Wu, Ke-yao Yu, Han Liu, Hong-zhen Lian
Talanta 2011 Volume 84(Issue 1) pp:141-147
Publication Date(Web):15 March 2011
DOI:10.1016/j.talanta.2010.12.041
An analytical method with the technique of QuEChERS (quick, easy, cheap, effective, rugged and safe) and gas chromatography (GC)/mass spectrometry (MS) in negative chemical ionization (NCI) has been developed for the determination of 17 pyrethroid pesticide residues in troublesome matrices, including garlic, onion, spring onion and chili. Pyrethroid residues were extracted with acidified acetonitrile saturated by hexane. After a modified QuEChERS clean-up step, the extract was analyzed by GC-NCI/MS in selected ion monitoring (SIM) mode. An isotope internal standard of trans-cypermethrin-D6 was employed for quantitation. Chromatograms of pyrethroids obtained in all these matrices were relatively clean and without obvious interference. The limits of detection (LODs) ranged from 0.02 to 6 μg kg−1 and recovery yields were from 54.0% to 129.8% at three spiked levels (20, 40 and 60 μg kg−1 for chili, and 10, 20 and 30 μg kg−1 for others) in four different matrices depending on the compounds determined. The relative standard deviations (RSDs) were all below 14%. Isomerization enhancement of pyrethroids in chili extract was observed and preliminarily explained, especially for acrinathrin and deltamethrin.
Co-reporter:Lin-feng Zhou;Jun-qin Qiao;Xin Ge
Research on Chemical Intermediates 2011 Volume 37( Issue 6) pp:617-625
Publication Date(Web):2011 July
DOI:10.1007/s11164-010-0234-2
A reliable reversed-phase high-performance liquid chromatographic method has been developed for analysis of related impurities in industrial phthalic anhydride (PA). Maleic acid (hydrolysis product of maleic anhydride), phthalimide, and benzoic acid were separated from phthalic acid (Pa, hydrolysis product of PA) on a C18 column by gradient elution with acetonitrile and 0.1% (v/v) aqueous perchloric acid solution. This method is simple, sensitive, and accurate, and has been successfully applied to quality control of PA for industrial use.
Co-reporter:Jun-Qin Qiao, Yan-Chu Bao, Ji-Hong Yang, Qin Jiang and Hong-Zhen Lian
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 2) pp:443-447
Publication Date(Web):November 25, 2009
DOI:10.1021/ie9014167
A combination of gas chromatography and mass spectrometry (GC-MS) was applied to separate and identify the relative substances in 2-chloroethyl phenyl sulfide (CEPS), an industrial intermediate formed in the synthesis of sulfinpyrazone. Six impurities, including 1,2-dichloroethane, thiophenol, diethylmalonate, tributylamine, diphenyl disulfide, and 1,2-dithiophenylethane, were verified. According to the production technique, the sources of all of these related impurities were analyzed, and some practical suggestions are put forward for their removal from or avoidance in CEPS. Furthermore, a technique involving high-performance liquid chromatography with UV detection (HPLC-UV) was developed to separate and determine thiophenol, the key impurity in CEPS. A linear standard curve was obtained for thiophenol in concentrations between 2.65 × 10−4 and 0.106 mg mL−1, and the detection limit of thiophenol was 1.32 × 10−4 mg mL−1. Excellent precision and accuracy were shown from the method validation, with relative standard deviations (RSDs) of less than 1.5% for both intra- and interday measurements, and recoveries between 95.4% and 97.0%. Based on the above merits, the proposed procedures of GC-MS and HPLC-UV can provide specific information on the impurities in CEPS, and therefore, these methods can be well applied to quality control in the industrial production of CEPS.
Co-reporter:Mei-Fei Wang, Jun-Qin Qiao, Zheng-Chun Qi, Yu-Na Wei, Hong-Zhen Lian, Tao Ding and Chong-Yu Shen
Industrial & Engineering Chemistry Research 2009 Volume 48(Issue 5) pp:2487-2492
Publication Date(Web):January 30, 2009
DOI:10.1021/ie801114c
A high performance liquid chromatography−photodiode array detection−electrospray ionization mass spectrometry (HPLC-PDA-ESIMS) method has been developed for separation and identification of relative substances in hydroquinone bis(2-hydroxyethyl) ether (HQEE), a kind of polyurethane chain extender synthesized by hydroquinone (HQ) and ethylene oxide (EO). HQEE and all relative substances were baseline separated on a reverse-phase C18 column with gradient elution of methanol and water. Of them, six relative substances were identified by ESIMS coupled with HPLC in positive ionization mode. The UV spectrum feature from online PDA and chromatographic retention behavior were adopted as evidence to conclude the rest relative substances. The results showed that EO combines with HQ in molar ratio of 1:1−5:1, and the tetra- (4:1) and penta-substitution (5:1) products are pairs of isomers, respectively. Therefore, the chromatographic fingerprint of industrial HQEE has been drawn on the basis of qualitative analysis of these products of different molar ratios.
Co-reporter:Xiang-Yun Li, Hong-Zhen Lian, Li Mao, Yi-Jun Chen, Xin Hu, Jun-qin Qiao, Dong Sheng
Talanta 2009 Volume 78(4–5) pp:1389-1394
Publication Date(Web):15 June 2009
DOI:10.1016/j.talanta.2009.02.032
A practice about preparing a once-used native state candidate rat serum reference material has been described for inductively coupled plasma atomic emission spectrometry (ICP-MS) determination of inorganic elements in biological matrices, which is independently packed, easy to use, non-lyophilized, without element-spiking, and with stable quality. Various dispersing and storing factors influencing the serum quality have been investigated including container material, sampling volume, packing mode and storage time. The contents of twelve main elements in the rat serum have been not only evaluated by ICP-MS but also verified by other analytical techniques. The probation of this unconventional candidate serum reference material by different laboratories has given very similar contents of 12 main trace elements in the serum, and proven its applicability to support quality assurance of biological sample analyses.
Co-reporter:Xin Ming, Shu-ying Han, Zheng-chun Qi, Dong Sheng, Hong-zhen Lian
Talanta 2009 Volume 79(Issue 3) pp:752-761
Publication Date(Web):15 August 2009
DOI:10.1016/j.talanta.2009.04.069
Although simple acids, replacing buffers, have been widely applied to suppress the ionization of weakly ionizable acidic analytes in reversed-phase liquid chromatography (RPLC), none of the previously reported works focused on the systematic studies about the retention behavior of the acidic solutes in this ion-suppression RPLC mode. The subject of this paper was therefore to investigate the retention behavior of monobasic weak acidic compounds using acetic, perchloric and phosphoric acids as the ion-suppressors. The apparent octanol–water partition coefficient (K″owK″ow) was proposed to calibrate the octanol–water partition coefficient (KowKow) of these weak acidic compounds, which resulted in a better linear correlation with log kwlog kw, the logarithm of the hypothetical retention factor corresponding to neat aqueous fraction of hydroorganic mobile phase. This log K″ow−log kwlog K″ow−log kw linear correlation was successfully validated by the results of monocarboxylic acids and monohydrating phenols, and moreover by the results under diverse experimental conditions for the same solutes. This straightforward relationship not only can be used to effectively predict the retention values of weak acidic solutes combined with Snyder–Soczewinski equation, but also can offer a promising medium for directly measuring KowKow data of these compounds via Collander equation. In addition, the influence of the different ion-suppressors on the retention of weak acidic compounds was also compared in this RPLC mode.
Co-reporter:Jun-Qin Qiao, Dong Sheng, Hong-Zhen Lian
Talanta 2009 Volume 77(Issue 5) pp:1573-1578
Publication Date(Web):15 March 2009
DOI:10.1016/j.talanta.2008.09.048
A high-performance liquid chromatographic method was proposed for the separation of relative impurities in industrial 3-methylflavone-8-carboxylic acid (MFCA) and its intermediate methyl 3-propionylsalicylate (MPS). Benzoic acid (BA), MPS, 6-chloro-3-methylflavone-8-carboxylic acid (MFCA-Cl) and methyl 5-chloro-3-propionylsalicylate (MPS-Cl) in MFCA, and MPS-Cl in MPS were respectively quantified by an external standard method. As results showed, the linearity of standard curves was excellent with the relative coefficients of over 0.999 for all the detected components, and the intra- and inter-day precisions of impurities determination were satisfactory with the relative standard deviation of not more than 8.0%. Under the selected experimental condition, the chromatographic fingerprints of MFCA and MPS were drawn synthetically, and the transfer of impurities in the stepwise reactions of MFCA manufacture was elucidated. The fingerprints have great potential in instructing the production of MFCA for industrial use and in conducting the conversion of relative impurities.
Co-reporter:Hongzhen Lian, Yuna Wei
Talanta 2007 Volume 71(Issue 1) pp:264-269
Publication Date(Web):15 January 2007
DOI:10.1016/j.talanta.2006.03.054
The chromatographic fingerprints of industrial o-toluic acid, m-toluic acid and p-toluic acid have been established by HPLC-UV detection according to their impurity groups. HPLC separation of all relative substances involved in the groups was developed on a Kromasil C18 column by using methanol–water–NH4Ac-HAc buffer (100 mM, pH 4.70) 15/65/20 (v/v/v) as the mobile phase at a flow rate of 1.5 mL/min, and detection was operated by UV adsorption at a wavelength of 254 nm. The ultraviolet spectra corresponding to each chromatographic peak were also recorded for further identification of all components. Whether the limits of relative impurities residues in a toluic acid product are qualified or not can be intuitively estimated by analyzing its chromatogram with comparison to the fingerprint. This protocol has successfully provided some Chinese manufacturers with a simple and feasible method for quality control of toluic acids for industrial use.
Co-reporter:Hongzhen Lian, Danli Li, Xiaoxian Wu, Liching Tian
Journal of Pharmaceutical and Biomedical Analysis 2005 Volume 37(Issue 2) pp:369-372
Publication Date(Web):23 February 2005
DOI:10.1016/j.jpba.2004.11.001
A reliable method for the simultaneous determination of phenolic preservatives parahydroxybenzoic acid, methyl, ethyl, propyl, butyl and pentyl parahydroxybenzoates in gelatin and vacant capsules for medical use has been developed by ion-suppression reversed-phase high performance liquid chromatography. Separation was carried out on a Kromasil C18 column by isocratic elution using methanol–perchloric acid (pH 2.0; 10 mM) (60:40, v/v) at a flow-rate of 1.0 ml min−1, and detection by UV absorbance at a wavelength of 254 nm. This method has been successfully applied to the routine analyses of these preservatives in the real samples.
Co-reporter:Hong-Zhen Lian;Wei-Han Wang;Dan-Ni Li
Journal of Separation Science 2005 Volume 28(Issue 11) pp:1179-1187
Publication Date(Web):28 JUN 2005
DOI:10.1002/jssc.200400092
In reversed-phase high performance liquid chromatography, the logarithm of the retention factor, log k, is usually correlated with the logarithm of the octanol-water partition coefficient, log Kow. The k and Kow of an ionizable analyte are greatly influenced by the mobile phase pH. In this paper, log kw of diprotic o-phthalic, 3-nitrophthalic, and 4-nitrophthalic acids, are obtained by extrapolation to pure aqueous fraction of mobile phase in ion-suppression reversed-phase high performance liquid chromatography with acetic acid and perchloric acid as the ion-suppressors. The Kow values of the three analytes are calibrated according to the apparent octanol-water partition coefficient, K ´´<?h -3dd>ow, under different pH conditions, and the log K ´´<?h -3dd>ow values show a much better correlation with log kw than do log Kow. The influences of two ion-suppressors, acetic and perchloric acids, on the retention behavior of these diprotic acids at different pH are contrasted. An abnormal trend is found in the k vs. pHw plot of the acetic acid system when the methanol content is low. A possible reason is that acetic acid is an even stronger organic modifier than methanol, besides being an ion-suppressor. The results make the selection of mobile phase for the separation of acidic compounds by ion-suppression reversed-phase high performance liquid chromatography direct, accurate, and practical.
Co-reporter:Xing-yu Long, Zi-jin Zhang, Jia-yuan Li, Dong Sheng and Hong-zhen Lian
Chemical Communications 2017 - vol. 53(Issue 33) pp:NaN4623-4623
Publication Date(Web):2017/03/28
DOI:10.1039/C7CC00540G
This work presents a sequential enrichment protocol, based on two self-designed cerium-based nanocomposite affinity probes, which not only can effectively separate phosphopeptides from non-phosphopeptides but can also selectively differentiate mono- and multi-phosphopeptides for direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric (MALDI-TOF MS) analysis.
Co-reporter:Xing-yu Long, Qun Song and Hong-zhen Lian
Journal of Materials Chemistry A 2015 - vol. 3(Issue 48) pp:NaN9339-9339
Publication Date(Web):2015/11/05
DOI:10.1039/C5TB01378J
Lichee-like core–shell structured magnetic lutetium phosphate (Fe3O4@LuPO4) affinity microspheres were successfully synthesized and well characterized. Based on the properties of great specificity and rapid separation, magnetic LuPO4 microspheres were applied to selectively enrich phosphopeptides for MALDI-TOF MS analysis. The enrichment performance of the prepared microspheres was demonstrated by tryptic digests of standard protein (β-casein), complex samples (tryptic digest mixture of β-casein and bovine serum albumin at different molar ratios of 1:10 to 1:50), and real biological samples (fresh pure milk and human serum), respectively. The enrichment ability of magnetic LuPO4 microspheres for phosphopeptides was very satisfying and the captured phosphopeptides with a sharp enhancement in MS signals were reliably identified based on the appearance of metastable ion peaks with poor resolution of the corresponding dephosphorylated peptides in the mass spectra. Enrichment of phosphopeptides by the Fe3O4@LuPO4 affinity microspheres provides a powerful approach for large scale phosphoproteome analysis.
Co-reporter:Peng Li, Yi-jun Chen, Hong-zhen Lian and Xin Hu
Journal of Analytical Atomic Spectrometry 2014 - vol. 29(Issue 10) pp:NaN1790-1790
Publication Date(Web):2014/07/14
DOI:10.1039/C4JA00149D
In this work, a centrifugal microfluidic platform with multiple solid phase extraction (SPE) units has been developed and successfully applied to separate Cr(VI) and Cr(III) with high throughput, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. Monolithic capillary columns, prepared by polymerization of N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AEAPTES) and tetraethoxysilane (TEOS), were integrated on a PDMS chip and used as the media for the selective extraction of Cr(VI). The aqueous solutions on the chip were driven by the centrifugal force produced by a centrifugal motor, so that high-throughput SPE is achieved by processing multiple samples simultaneously. The adsorption and elution conditions of Cr(VI) onto the monolithic capillary column, and the rotation speed of the centrifugal motor were well studied. The feasibility of the proposed protocol was validated by certified reference materials and real water samples. In contrast to the traditional speciation analysis procedure, the species separation of eight samples can be finished within 10 min on the established centrifugal microfluidic platform. This device possessing the advantages of portability and simplicity provides a potential application for field sampling and pretreatment.
Co-reporter:
Analytical Methods (2009-Present) 2014 - vol. 6(Issue 12) pp:
Publication Date(Web):
DOI:10.1039/C4AY00438H
A sequential solid phase microextraction (SPME) system consisting of two monolithic capillary columns was developed for simultaneous separation and preconcentration of inorganic arsenic, followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AEAPTES) incorporated organic–inorganic hybrid monolithic column was prepared in situ by sol–gel technology in a fused capillary and employed as the extraction medium for SPME in this system, because the amino active sites on the synthesized monolith possess a high adsorption selectivity for As(V). With the on-line design of dual columns and an oxidation coil, As(V) is quantitatively extracted by the first column, and As(III) in the effluent can be quantitatively extracted by the second column after oxidization to As(V) by a make-up KMnO4 solution. The retained As(V) or As(III) is then sequentially eluted by diluted HNO3 and introduced to ICP-MS for determination. In this work, the parameters effecting the retention and elution of As(V) and As(III) were optimized in detail. On-line SPME of 1 mL sample solution gave a signal enhancement factor of 60 for both As(V) and As(III) using the system. The precision (RSD) for six replicate measurements of 1 μg L−1 As(V) and As(III) were 3.8% and 3.2%, respectively. The limits of detection (LODs, defined as three times the signal-to-noise ratio) for As(V) and As(III) were 0.005 μg L−1. The developed method was successfully applied to the speciation analysis of inorganic arsenic in drinking and environmental waters with satisfactory recoveries.
Co-reporter:Wen-Sheng Zou;Jing Yang;Ting-Ting Yang;Xin Hu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 11) pp:NaN4727-4727
Publication Date(Web):2012/02/21
DOI:10.1039/C2JM15139A
In recent decades, considerable efforts related to the study of 2,4,6-trinitrotoluene (TNT) have been focused on either developing ultraselective and ultrasensitive methods for real-time analytical detection or exploiting highly efficient and green technologies for treatment of contaminated waters. In the present work, combining the magnetic response property of Fe3O4 nanoparticles with the chemosensory property of quantum dots (QDs), Fe3O4 magnetic nanoparticles and Mn-doped ZnS QD nanocomposites (MNPs/QD NCs) have been synthesized and used for room-temperature phosphorescence (RTP) sensing and magnetic separation of captured ultratrace TNT in water. Notably, magnetic-RTP MNPs/QD NCs were found as photo-driven enzyme mimetics for degradation of TNT through Haber–Weiss cycle reactions for the first time. Meanwhile, MNPs/QD NCs exhibited a highly selective response for TNT with detection limit down to 12.5 nM through the quenching of 4T1–6A1 transition emission. By in situ monitoring electron paramagnetic resonance (EPR) signals, production of hydroxyl radical (OH˙) is attributed fundamentally to the catalytic reactions occurring at metal ions on the surface of Fe3O4 nanoparticles rather than those released from the MNPs into a solution. The proposed methods, as well as being suitable for detecting ultratrace TNT and distinguishing different nitro-compounds, could be used as one of the most promising approaches for developing highly efficient degradation of organics contaminated waters to generate treated waters which could be easily reused or released into the environment without any harmful effects.
METHANONE](http://img.cochemist.com/ccimg/75700/75625-24-0.png)
METHANONE](http://img.cochemist.com/ccimg/75700/75625-24-0_b.png)
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