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ABSTRACT: A rapid and sensitive method based on polymer monolithic capillary microextraction on-line combined with micro-concentric nebulization inductively coupled plasma mass spectrometry has been developed for the determination of trace/ultra-trace rare earth elements in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by Scanning Electron Microscope and Fourier Transform Infrared Spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume and coexisting ions were investigated in detail. Under the optimal conditions, the limits of detection for rare earth elements were in the range of 0.08 (Er)-0.97 ng L(-1) (Nd) with a sampling frequency of 8.5 h(-1) , and the relative standard deviations were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng L(-1) , n = 7). The proposed method was successfully applied to the analysis of trace/ultra-trace rare earth elements in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive and favorable for the analysis of trace/ultra-trace rare earth elements in biological samples with limited sample volume. This article is protected by copyright. All rights reserved.
Journal of Separation Science 04/2013; · 2.73 Impact Factor
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ABSTRACT: A new concept of "dual-phase dual stir bar sorptive extraction (SBSE)" was proposed to simultaneously extract six preservatives with different polarities (logKo/w values of 1.27-3.41), namely, benzoic acid (BA), sorbic acid (SA), methyl p-hydroxybenzoate (MP), ethyl p-hydroxybenzoate (EP), propyl p-hydroxybenzoate (PP), and butyl p-hydroxybenzoate (BP). The dual-phase dual SBSE apparatus was consisted of two differently coated stir bars, a 3-aminopropyltriethoxysilane (APTES)-hydroxy-terminated silicone oil (OH-TSO)-coated stir bar that was prepared by sol-gel technique and a C(18) silica (C(18))-polydimethylsiloxane (PDMS)-coated stir bar that was prepared by adhesion. In dual-phase dual SBSE, the two stir bars with different coatings were placed in the same sample solution for the simultaneous extraction of the target analytes with different polarities, and then the bars were desorbed in the same desorption solvent. The extraction performance of the dual-phase dual SBSE for the six preservatives was evaluated by comparing with the conventional SBSE (individual stir bar) with different coatings, including commercial PDMS, homemade PDMS, C(18)-APTES-OH-TSO, APTES-OH-TSO, and C(18)-PDMS. The experimental results showed that the dual-phase dual SBSE had the highest extraction efficiency for the six target preservatives. Based on this fact, a novel method by combining the dual-phase dual SBSE which was consisted of the APTES-OH-TSO-coated and C(18)-PDMS-coated stir bars with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was developed for the simultaneous analysis of six target beverage preservatives in beverages. Under optimal conditions, the limits of detection (LODs) for six target preservatives ranged from 0.6 to 2.7μgL(-1) with the relative standard deviations (RSDs) of 4.6-9.2% (C(BA,SA)=5μgL(-1),C(MP)=20μgL(-1),C(EP,PP,BP)=10μgL(-1), n=7). The enrichment factors (EFs) were approximately 16-42-fold (theoretical EF was 50-fold). The proposed method was validated by the analysis of six target preservatives in three kinds of beverage samples, and the recoveries for the spiked samples were in the range of 76.6-118.6% for cola, 74.6-17.5% for orange juice, and 83.0-119.1% for herbal tea, respectively.
Journal of chromatography. A 01/2013; · 4.19 Impact Factor
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ABSTRACT: In this work, a new method of polydimethylsiloxane/polythiophene (PDMS/PTH) coated stir bar sorptive extraction (SBSE) coupled to liquid desorption-large volume injection-gas chromatography-flame photometric detection (LD-LVI-GC-FPD) was proposed for the determination of organophosphorus pesticides (OPPs, including phorate, fenitrothion, malathion, parathion and quinalphos) in environmental water samples. Polythiophene was synthesized by chemical oxidative polymerization method, and the PDMS/PTH coated stir bar was prepared by sol-gel technique. The preparation reproducibility of PDMS/PTH coated stir bar was good with the relative standard deviations (RSDs) ranging from 3.9% to 8.1% (n=7) in one batch, and from 5.9% to 14.9% (n=6) among different batches. To get the best extraction performance for OPPs, the operation parameters affecting the extraction efficiency of SBSE, including extraction time, desorption time, stirring rate and ionic strength, were investigated. Under the optimal conditions, the limits of detection (S/N=3) were found to be in the range of 0.011-0.038μg/L for the five target OPPs, and the linear range was from 0.2 to 100μg/L for phorate and 0.1-100μg/L for other four OPPs. The RSDs of the proposed method were in the range of 4.0-9.8% (n=8, c=1μg/L) and the enrichment factors were varied from 56.7 to 80.9-fold (theory enrichment factor was 100-fold). The proposed method was applied to the analysis of OPPs in East Lake water and ground water samples with recovery in the range of 77.7-119.8% and 79.1-109.8% for the spiked East Lake water and ground water samples, respectively.
Journal of chromatography. A 12/2012; · 4.19 Impact Factor
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ABSTRACT: A new method of phase transfer hollow fiber liquid phase microextraction (PT-HF-LPME) combined with electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) has been developed for the determination of trace Co, Pd, Cd and Bi in environmental and biological samples. In PT-HF-LPME, an intermediate solvent (1-butanol) was added into the sample solution to ensure the maximum contact area between the target metal ions and the chelating reagent (8-hydroxyquinoline, 8-HQ), which accelerated the formation of 8-HQ-metal complexes and their subsequent extraction by extraction solvent (toluene). The experimental parameters affecting the extraction efficiency of PT-HF-LPME for the target metals were studied by simplex optimization and orthogonal array design (OAD) experiments. Under the optimized conditions, the enrichment factors for Co, Pd, Cd and Bi were 110, 393, 121 and 111-fold, respectively, the limits of detection (LODs, 3σ) ranged from 3.7 to 8.3ngL(-1). The relative standard deviations (RSDs, c=0.5ngmL(-1), n=7) were 8.7, 6.2, 12.4 and 12.9% for Co, Pd, Cd and Bi, respectively. To validate the accuracy of the proposed method, two Certified Reference Materials of GSBZ50009-88 Environment Water and GBW09103 Human Urine were analyzed, and the results obtained for Cd were in good agreement with the certified values. Finally, the developed method was successfully applied to the analysis of Co, Pd, Cd and Bi in lake water and human urine samples.
Talanta 11/2012; 101:516-23. · 3.79 Impact Factor
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ABSTRACT: A new phenylalanine derivative (l-N-(2-hydroxy-propyl)-phenylalanine, l-HP-Phe) was synthesized and its chelate with Cu(II) (Cu(II)-(l-HP-Phe)(2)) was used as the chiral selector for the ligand-exchange (LE) chiral separation of d,l-selenomethionine (SeMet) in selenized yeast samples by micelle electrokinetic capillary chromatography (MEKC). In order to improve the sensitivity of MEKC-UV, two-step preconcentration strategy was employed, off-line solid phase extraction (SPE) and on-line large volume sample stacking (LVSS). d,l-SeMet was first retained on the Cu(II) loaded mesoporous TiO(2), then eluted by 0.1mL of 5molL(-1) ammonia, and finally introduced for MEKC-UV analysis by LVSS injection after evaporation of NH(3). With the enrichment factors of 1400 and 1378, the LODs of 0.44 and 0.60ngmL(-1) for l-SeMet and d-SeMet was obtained, respectively. The developed method was applied to the analysis of d,l-SeMet in a certified reference material of SELM-1 and a commercial nutrition yeast, and the results showed that most of SeMet in the SELM-1 selenized yeast was l isomer and the recovery for l and d isomers in the spiked commercial nutrition yeast was 96.3% and 103%, respectively. This method is featured with low running cost, high sensitivity and selectivity, and exhibits application potential in chiral analysis of seleno amino acids in real world samples.
Journal of chromatography. A 10/2012; · 4.19 Impact Factor
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ABSTRACT: A poly(dimethylsiloxane) (PDMS)/β-cyclodextrin (β-CD)/divinylbenzene (DVB)-coated stir bar was prepared by the sol-gel technique for the stir bar sorptive extraction (SBSE) of four estrogens from animal-derived foods, followed by liquid desorption (LD) and high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. The influence of the coating composition on SBSE of target estrogens was investigated by an orthogonal experiment design, and the prepared PDMS/β-CD/DVB-coated stir bars show good reproducibility. Under the optimal experimental conditions, the limits of detection (S/N = 3) of the developed PDMS/β-CD/DVB SBSE-LD-HPLC-UV method were 0.21-1.6 μg/L for the target estrogens with enrichment factors of 19-51-fold, the dynamic linear range was 2-2000 μg/L, and the relative standard deviations of the method ranged from 6.0% to 9.7% (n = 8, c = 100 μg/L) and from 8.4% to 11.7% (n = 8, c = 10 μg/L). The developed method was simple, sensitive, and selective and was successfully applied to the analysis of estrogens in pork and chicken samples.
Journal of Agricultural and Food Chemistry 10/2012; · 2.82 Impact Factor
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ABSTRACT: In this study, novel off/on-site stir bar sorptive extraction (SBSE) approaches with a home-made portable electric stirrer have been developed for the analysis of polycyclic aromatic hydrocarbon compounds (PAHs). In these approaches, a miniature battery-operated electric stirrer was employed to provide agitation of sample solutions instead of the commonly used large size magnetic stirrer powered by alternating current in conventional SBSE process, which could extend the SBSE technique from the conventional off-site analysis to the on-site sampling. The applicability of the designed off/on-site SBSE sampling approaches was evaluated by polydimethylsiloxane (PDMS) coating SBSE-high performance liquid chromatography-fluorescence detection (HPLC-FLD) analysis of six target PAHs in environmental water. The home-made portable electric stirrer is simple, easy-to-operate, user friendly, low cost, easy-to-be-commercialized, and can be processed in direct immersion SBSE, headspace sorptive extraction (HSSE) and continuous flow (CF)-SBSE modes. Since the stir bar was fixed onto the portable device by magnetic force, it is very convenient to install, remove and replace the stir bar, and the coating friction loss which occurred frequently in conventional SBSE process could be avoided. The parameters affecting the extraction of six target PAHs by the home-made portable SBSE sampling device with different sampling modes were studied. Under the optimum extraction conditions, good linearity was obtained by all of three SBSE extraction modes with correlation coefficient (R) higher than 0.9971. The limits of detection (LODs, S/N=3) were 0.05-3.41ngL(-1) for direct immersion SBSE, 0.03-2.23ngL(-1) for HSSE and 0.09-3.75ngL(-1) for CF-SBSE, respectively. The proposed portable PDMS-SBSE-HPLC-FLD method was applied for the analysis of six target PAHs in East Lake water, and the analytical results obtained by on-site SBSE sampling were in good agreement with that obtained by off-site SBSE sampling. The accuracy of the developed method was evaluated by recovery test and the recoveries for the spiked sample were found to be in the range of 87.1-122.8% for off-site CF-SBSE, 88.8-114.3% for on-site sampling, and 87.7-123.6% for off-site SBSE, respectively. The developed method is one of the most sensitive methods for PAHs determination and the home-designed SBSE system is feasible for the field sampling.
Journal of chromatography. A 08/2012; 1260:16-24. · 4.19 Impact Factor
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ABSTRACT: In this paper, a new method of nanometer-sized alumina packed microcolumn SPE combined with field-amplified sample stacking (FASS)-CE-UV detection was developed for the speciation analysis of inorganic selenium in environmental water samples. Self-synthesized nanometer-sized alumina was packed in a microcolumn as the SPE adsorbent to retain Se(IV) and Se(VI) simultaneously at pH 6 and the retained inorganic selenium was eluted by concentrated ammonia. The eluent was used for FASS-CE-UV analysis after NH(3) evaporation. The factors affecting the preconcentration of both Se(IV) and Se(VI) by SPE and FASS were studied and the optimal CE separation conditions for Se(IV) and Se(VI) were obtained. Under the optimal conditions, the LODs of 57 ng L(-1) (Se(IV)) and 71 ng L(-1) (Se(VI)) were obtained, respectively. The developed method was validated by the analysis of a certified reference material of GBW(E)080395 environmental water and the determined value was in a good agreement with the certified value. It was also successfully applied to the speciation analysis of inorganic selenium in environmental water samples, including Yangtze River water, spring water, and tap water.
Electrophoresis 08/2012; 33(19-20):2953-60. · 3.30 Impact Factor
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ABSTRACT: In this work, partially sulfonated polystyrene-titania (PSP-TiO(2)) organic-inorganic hybrid stir bar coating was prepared by sol-gel and blending methods, and a new method of PSP-TiO(2) coating stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) was established for the analysis of seleno-amino acids (selenocystine (SeCys(2)), methylseleno-cysteine (MeSeCys), selenomethionine (SeMet) and selenoethionine (SeEt)) and seleno-oligopeptides (γ-glutamyl-Se-methyl-selenocysteine (γ-GluMeSeCys) and selenodiglutathione (GS-Se-SG)) in biological samples. The prepared high polar PSP-TiO(2) hybrid coating avoided the swelling of PSP and cracking of TiO(2) coating by combining the good film-forming property of PSP with the high mechanical strength of TiO(2). The scanning electron microscope (SEM) showed that no obvious swelling and damage occurred for the PSP-TiO(2) hybrid stir bar coating after 30 extraction/desorption cycles. The preparation reproducibility of PSP-TiO(2) coated stir bar, evaluated with the relative standard deviations (RSDs), was in the range of 6.7-12.6% (n=5) in one batch, and 9.9-17.6% (n=7) among different batches. The limits of detection (LODs) of the developed method for six target selenium species were in the range of 50.2-185.5 ngL(-1) (as (77)Se) and 45.9-158.8 ngL(-1) (as (82)Se) with the RSDs within 4.9-11.7%. The dynamic linear range was found to cover three orders of magnitude with correlation coefficient of 0.9995-0.9999. The developed method was applied for the analysis of Certified Reference Material SELM-1 selenium enriched yeast and the determined values were in good agreement with the certified values. The method has also been applied for the analysis of seleno-amino acids and seleno-oligopeptides in human urine and garlic samples. Different from the conventional organic polymer SBSE coatings (such as polydimethylsiloxane, PDMS), the extraction mechanism of PSP-TiO(2) organic-inorganic hybrid SBSE coating was based on the cation exchange interaction, which made it feasible to directly extract high polar seleno-amino acids and seleno-oligopeptides in biological samples without derivatization. This coating could also be suitable for stir bar sorptive extraction of other cationic compounds from the environmental and biological samples.
Journal of chromatography. A 08/2012; 1256:32-9. · 4.19 Impact Factor
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ABSTRACT: A new method of solidified floating organic drop microextraction (SFODME) combined with electrothermal vaporization (ETV)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of trace heavy metals in environmental water samples with sodium diethyldithiocarbamate (DDTC) as both chelating reagent in SFODME and chemical modifier in ETV. The factors affecting the microextraction efficiency were studied in detail and the optimal extraction conditions were established. Under the optimal conditions, the limits of detection (LODs) for SFODME-ETV-ICP-MS determination of Co, Pd, Cd, Hg, Pb and Bi were found to be 0.0060, 0.0091, 0.0020, 0.0041, 0.0170 and 0.0041 ng mL(-1), respectively, with the relative standard deviations (RSDs) of 2.8-10.0% (c=0.5 ng mL(-1), n=7). The developed method was successfully applied to the analysis of six target metals in Yangtze River and East Lake water samples with recoveries ranging from 77.7 to 119.1%. To validate the accuracy of the method, a certified reference material of Environmental Water (GSBZ50009-88) was analyzed and the determined values were in good agreement with the certified values.
Talanta 05/2012; 94:70-6. · 3.79 Impact Factor
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ABSTRACT: We report here the preparation of high-magnetization Fe(3)O(4)@SiO(2)@TiO(2) nanoparticles for solid phase extraction of trace amounts of Cd(II), Cr(III), Mn(II) and Cu(II) from environmental waters. The prepared nanoparticles were characterized by scanning electron micrograph (SEM) and transmission electron microscopy (TEM). The high-magnetization nanoparticles carrying the target metals could be easily and fast separated from the aqueous solution simply by applying an external magnetic field while no filtration or centrifugation was necessary. A light-induced hydroxide ion emitter, molecular malachite green carbinol base (MGCB) was applied to adjust pH value of solution for quantitative adsorption instead of the conventional used buffer. In the presence of UV light, MGCB gives out OH(-) ions, and this leads to an increase in the pH value without the aid of buffer solution. Using high-magnetization Fe(3)O(4)@SiO(2)@TiO(2) nanoparticles as the extraction material and the light-induced MGCB for pH adjustment, we developed an efficient and convenient two-step method for separation/preconcentration trace amounts of Cd(II), Cr(III), Mn(II) and Cu(II) in environmental water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The parameters affecting the extraction such as MGCB concentration, exposal time, sample volume, eluent condition, and interfering ions have been investigated in detail. Under the optimized conditions, the limits of detection for Cd(II), Cr(III), Mn(II) and Cu(II) were 4.0, 2.6, 1.6 and 2.3 ng L(-1), respectively, and the relative standard deviations (RSDs, c=1 μg L(-1), n=7) were 3.6%, 4.5%, 4.0 and 4.1%, respectively. The proposed method has been validated using certified reference materials, and it has been successfully applied in the determination of trace Cd(II), Cr(III), Mn(II) and Cu(II) in environmental water samples.
Talanta 05/2012; 94:278-83. · 3.79 Impact Factor
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ABSTRACT: In this study, a sensitive, selective and reliable analytical method by combining zirconia (ZrO₂) coated stir bar sorptive extraction (SBSE) with large volume sample stacking capillary electrophoresis-indirect ultraviolet (LVSS-CE/indirect UV) was developed for the direct analysis of chemical warfare agent degradation products of alkyl alkylphosphonic acids (AAPAs) (including ethyl methylphosphonic acid (EMPA) and pinacolyl methylphosphonate (PMPA)) and methylphosphonic acid (MPA) in environmental waters. ZrO₂ coated stir bar was prepared by adhering nanometer-sized ZrO₂ particles onto the surface of stir bar with commercial PDMS sol as adhesion agent. Due to the high affinity of ZrO₂ to the electronegative phosphonate group, ZrO₂ coated stir bars could selectively extract the strongly polar AAPAs and MPA. After systematically optimizing the extraction conditions of ZrO₂-SBSE, the analytical performance of ZrO₂-SBSE-CE/indirect UV and ZrO₂-SBSE-LVSS-CE/indirect UV was assessed. The limits of detection (LODs, at a signal-to-noise ratio of 3) obtained by ZrO₂-SBSE-CE/indirect UV were 13.4-15.9 μg/L for PMPA, EMPA and MPA. The relative standard deviations (RSDs, n=7, c=200 μg/L) of the corrected peak area for the target analytes were in the range of 6.4-8.8%. Enhancement factors (EFs) in terms of LODs were found to be from 112- to 145-fold. By combining ZrO₂ coating SBSE with LVSS as a dual preconcentration strategy, the EFs were magnified up to 1583-fold, and the LODs of ZrO₂-SBSE-LVSS-CE/indirect UV were 1.4, 1.2 and 3.1 μg/L for PMPA, EMPA, and MPA, respectively. The RSDs (n=7, c=20 μg/L) were found to be in the range of 9.0-11.8%. The developed ZrO₂-SBSE-LVSS-CE/indirect UV method has been successfully applied to the analysis of PMPA, EMPA, and MPA in different environmental water samples, and the recoveries for the spiked water samples were found to be in the range of 93.8-105.3%.
Journal of chromatography. A 05/2012; 1247:49-56. · 4.19 Impact Factor
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ABSTRACT: We have immobilized iminodiacetic acid on mesoporous Fe3O4@SiO2 microspheres and used this material for efficient and cost effective method of magnetic solid phase extraction (SPE) of trace
levels of Cd, Mn and Pb. The microspheres were characterized by infrared spectroscopy, scanning electron microscopy and transmission
electron microscopy. The loaded microspheres can be easily separated from the aqueous sample solution by applying an external
magnetic field. The effects of pH, sample volume, concentration and volume of eluent, and of interfering ions were investigated
in detail. The method has detection limit of 0.16, 0.26 and 0.26ngL−1 for the ions of Cd, Mn and Pb, respectively, and the relative standard deviations (RSDs, c = 1μgL−1, n = 7) are 4.8%, 4.6% and 7.4%. The method was successfully applied to the determination of these metals in biological and
environmental samples using ICP-MS. Two certified reference materials were analyzed, and the results coincided well with the
certified values.
FigureMesoporous Fe3O4@SiO2@IDA magnetic particles for fast and selective magnetic solid phase extraction of trace Cd, Mn and Pb from environmental and
biological samples followed by inductively coupled plasma mass spectrometry detection.
KeywordsHigh-magnetization mesoporous microspheres–Fe3O4@SiO2@ iminodiacetic acid–Cadmium, manganese and lead–Solid phase extraction–Inductively coupled plasma mass spectrometry
Microchimica Acta 04/2012; 175(1):121-128. · 3.03 Impact Factor
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ABSTRACT: The chemical modification of diethyldithiocarbamate (DDTC) in electrothermal vaporization inductively coupled plasma optical
emission spectrometry (ETV-ICP-OES) and in electrothermal atomic absorption spectrometry (ETAAS) was comparatively investigated.
The experimental results indicated that the formation of Cr- and Ni-DDTC chelates enhanced significantly the emission signals
of Cr and Ni in ETV-ICP-OES, but decreased the absorption signal of Cr and Ni in ETAAS. The different role of DDTC in ETV-ICP-OES
and ETAAS was attributed to the different functions of the graphite furnace in the two techniques. The graphite furnace was
used as both a vaporizer and an atom-vessel for analytes in ETAAS, but only used as a vaporizer for the sample in ETV-ICP-OES.
Thermal gravimetric analysis of Cr- and Ni-DDTC chelates and UV-Vis analysis of the sample vapor collected in CHCl3 after vaporization of their chelates from the graphite furnace indicated that the analytes were vaporized and transported
into ICP as their chelates. In addition, the vaporization mechanism of Cr and Ni was also briefly discussed.
Microchimica Acta 04/2012; 153(3):211-217. · 3.03 Impact Factor
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ABSTRACT: A new method using nanoparticle TiO2 as solid-phase extractant coupled with ICP-AES was proposed for simultaneous determination of trace elements. The adsorption
behavior of nanometer TiO2 towards Cu, Cr, Mn and Ni was investigated by ICP-AES, and the adsorption pH curves, adsorption isotherms and adsorption
capacities were obtained. It was found that the adsorption rates of the metal ions studied were more than 90% in pH 8.0∼9.0,
and 2.0 mol L–1 HCl was sufficient for complete elution. Nanometer TiO2 possesses a significant capacity for the sorption of the metal ions studied which is higher than the capacity of silica,
the commonly used extractant. The method has been applied to the analysis of some environmental samples with satisfactory
results.
Fresenius Journal of Analytical Chemistry 04/2012; 368(6):638-640.
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ABSTRACT: Cd(II) imprinted 3-mercaptopropyltrimethoxysilane (MPTS)-silica coated stir bar was prepared by sol-gel technique combining with a double-imprinting concept for the first time and was employed for stir bar sorptive extraction (SBSE) of trace Cd(II) from water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. A tetramethoxysilane (TMOS) coating was first in situ created on the glass bar surface. Afterward, a sol solution containing MPTS as the functional precursor, ethanol as the solvent and both Cd(II) and surfactant micelles (cetyltrimethylammonium bromide, CTAB) as the template was again coated on the TMOS bar. The structures of the stir bar coating were characterized by FT-IR spectroscopy. Round-bottom vial was used for the extraction of Cd(II) by SBSE to avoid abrasion of stir bar coatings. The factors affecting the extraction of Cd(II) by SBSE such as pH, stirring rate and time, sample/elution volume and interfering ions have been investigated in detail, and the optimized experimental parameters were obtained. Under the optimized conditions, the adsorption capacities of non-imprinted and imprinted coating stir bars were found to be 0.5 μg and 0.8 μg bar(-1). The detection limit (3σ) based on three times standard deviations of the method blanks by 7 replicates was 4.40 ng L(-1) and the relative standard deviation (RSD) was 3.38% (c=1 μg L(-1), n=7). The proposed method was successfully applied for the analysis of trace Cd(II) in rain water, East Lake and Yangtze River water. To validate the proposed method, certified reference material of GSBZ 50009-88 environmental water was analyzed and the determined value is in a good agreement with the certified value. The developed method is rapid, selective, sensitive and applicable for the analysis of trace Cd(II) in environmental water samples.
Analytica chimica acta 04/2012; 723:54-60. · 4.31 Impact Factor
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ABSTRACT: A novel method based on in-tube hollow fiber-solid phase microextraction (in-tube HF-SPME) on-line coupled with ion pair reversed phase high performance liquid chromatography (IP-RP-HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) was developed for arsenic speciation. Partially sulfonated poly(styrene) (PSP) and mixed-sol of 3-mercapto propyltrimethoxysilane (MPTS) and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPTS) were prepared and immobilized in the pores and the inner surface of polypropylene hollow fiber (HF). The prepared MPTS-AAPTS/PSP immobilized HF was characterized by FT-IR spectroscopy and scanning electron microscope (SEM). With arsenite (As(III)), arsenate (As(V)), monomethylarsonic acid (MMA), dimethylarsenic acid (DMA), arsenobetaine (AsB) and arsenocholine (AsC) as model arsenic species, a series of factors that influence the extraction of target arsenic species by in-tube HF-SPME, including pH value, sample volume and flow rate, elution conditions and interference of co-existing ions were investigated in details, and the conditions for subsequent HPLC-ICP-MS determination were also optimized. Under the optimal conditions, the sampling frequency was 6.5 h⁻¹, the detection limits for six target arsenic species were in the range of 0.017-0.053 μg L⁻¹ with the relative standard deviations (c(As(V),MMA)=0.1 μg L⁻¹, c(As(III),DMA,AsB,AsC)=0.5 μg L⁻¹, n=5) ranging in 3.1-8.7%, and the enrichment factors were varied from 4 to 19-fold. To validate the accuracy of this method, certified reference materials DORM-2 (dogfish) and CRM No. 18 (human urine) were analyzed, and the determined values were in good agreement with the certified values. The proposed method was also successfully applied for arsenic speciation in human urine samples, and the recoveries for the spiked samples were in the range of 92.6-107%. The self-designed in-tube HF-SPME-HPLC-ICP-MS system shows high efficiency and good stability, and the proposed method is sensitive and suitable for simultaneous speciation of organic and inorganic arsenic species (including anions and cations) in biological samples.
Journal of chromatography. A 03/2012; 1227:19-28. · 4.19 Impact Factor
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ABSTRACT: A simple, rapid, sensitive, inexpensive and less sample consuming method of C(18)-stir bar sorptive extraction (SBSE)-high performance liquid chromatography (HPLC)-tandem mass spectrometry (MS/MS) was proposed for the determination of six sulfonamides in milk and milk powder samples. C(18) silica particles coated stir bar was prepared by adhesion method, and two kinds of adhesive glue, polydimethylsiloxane (PDMS) sol and epoxy glue were tried. It was found that the C(18)-coated stir bar prepared by PDMS sol as adhesive glue is more robust than that prepared by epoxy glue when liquid desorption was employed, in terms of both lifetime and organic solvent tolerance. The preparation of C(18) stir bar was simple with good mechanic strength and the stir bar could be reused for more than 20 times. Granular coating has relatively high specific surface area and is propitious to sorptive extraction based process. Compared to conventional PDMS SBSE coating, C(18) coating shows good affinity to the target polar/weak polar sulfonamides. To achieve optimum SBSE extraction performance, several parameters including extraction and desorption time, ionic strength, sample pH and stirring speed were investigated. The detection limits of the proposed method for six sulfonamides were in the range of 0.9-10.5 μg/L for milk and 2.7-31.5 μg/kg for milk powder. Good linearities were obtained for sulfonamides with the correlation coefficients (R) above 0.9922. Finally, the proposed method was successfully applied to the determination of sulfonamides in milk and milk powder samples and satisfied recoveries of spiked target compounds in real samples were obtained.
Talanta 02/2012; 90:77-84. · 3.79 Impact Factor
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ABSTRACT: A fast and simple method for analysis of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II) in environmental and biological samples was developed by combining magnetic solid phase extraction (MSPE) with inductively coupled plasma-optical emission spectrometry (ICP-OES) detection. Dithizone modified silica-coated magnetic Fe(3)O(4) nanoparticles (H(2)Dz-SCMNPs) were prepared and used for MSPE of trace amounts of Cr(III), Cu(II), Pb(II) and Zn(II). The prepared magnetic nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The factors affecting the extraction of the target metal ions such as pH, sample volume, eluent, and interfering ions had been investigated and the adsorption mechanism of the target metals on the self-prepared H(2)Dz-SCMNPs was investigated by FT-IR and X-ray photo electron spectroscopy (XPS). Under the optimized conditions, the detection limits of the developed method for Cr(III), Cu(II), Pb(II) and Zn(II) were 35, 11, 62, and 8ngL(-1), respectively, with the enrichment factor of 100. The relative standard deviations (RSDs, c=10μgL(-1), n=7) were in the range of 1.7-3.1% and the linear range was 0.1-100μgL(-1). The proposed method had been validated by two certified reference materials (GSBZ50009-88 environmental water and GBW07601 human hair), and the determined values were in good agreement with the certified values. The method was also applied for the determination of trace metals in real water and human hair samples with recoveries in the range of 85-110% for the spiked samples. The developed MSPE-ICP-OES method has the advantages of simplicity, rapidity, selectivity, high extraction efficiency and is suitable for the analysis of samples with large volume and complex matrix.
Talanta 01/2012; 88:507-15. · 3.79 Impact Factor
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ABSTRACT: In this paper, a novel sample pretreatment technique termed phase transfer based liquid-liquid-liquid microextraction (PT-LLLME) was proposed for the simultaneous extraction of inorganic and organic mercury species. In PT-LLLME, an intermediate solvent (acetonitrile) was added into the donor phase to improve the contacting between target mercury species and complexing reagent. Meanwhile, a membrane supported (MS)-LLLME unit was designed to realize the PT-LLLME procedure. By using nylon membrane as supporting carrier, larger than 50 μL of acceptor solution could be hung up. Following PT/MS-LLLME, the acceptor solutions were directly analyzed by large volume sample stacking capillary electrophoresis/ultraviolet detection (LVSS-CE/UV). Accordingly, a new method of PT/MS-LLLME combined with LVSS-CE/UV was developed for the simultaneous speciation of inorganic and organic mercury species. Parameters affecting the extraction efficiency of PT/MS-LLLME were investigated in details. Under the optimized conditions, enrichment factors (EFs) ranging from 160- to 478-fold were obtained for the extraction of target mercury species by PT/MS-LLLME. By combining PT/MS-LLLME with LVSS-CE/UV, EFs were magnified up to 12,138-fold and the limits of detection (at a signal-to-noise ratio of 3) were at sub ppb level. The established approach of PT/MS-LLLME-LVSS-CE/UV was successfully applied to simultaneous determination of inorganic and organic mercury species in biological samples and environmental water samples.
Journal of chromatography. A 11/2011; 1218(52):9414-21. · 4.19 Impact Factor
