摘要：
A novel method for the selective determination of methylmercury (MeHg) was developed by one-step displacement dispersive liquid-liquid microextraction (D-DLLME) coupled with graphite furnace atomic absorption spectrometry. In the proposed method, Cu(II) reacted with diethyldithiocarbamate (DDTC) to form Cu-DDTC complex, which was used as the chelating agent instead of DDTC for the dispersive liquid-liquid microextraction (DLLME) of MeHg. Because the stability of MeHg-DDTC is higher than that of Cu-DDTC, MeHg can displace Cu from the Cu-DDTC complex and be preconcentrated in a single DLLME procedure. MeHg could be extracted into the extraction solvent phase at pH 6 while Hg(II) remained in the sample solution. Potential interference from co-existing metal ions with lower DDTC complex stability was largely eliminated without the need of any masking reagent. Under the optimal conditions, the limit of detection of this method was 13.6 ng L-1 (as Hg), and an enhancement factor of 81 was achieved with a sample volume of 5.0 mL. The proposed method was successfully applied for the determination of trace MeHg in some environmental samples with satisfactory results. (C) 2015 Elsevier B.V. All rights reserved.
作者机构：
[Yang, Enjian; Kang, Caiyan; Liang, Pei] Cent China Normal Univ, Coll Chem, Key Lab Pesticide Chem Biol, Minist Educ, Wuhan 430079, Peoples R China.;[Du, Dan; Lin, Yuehe; Ge, Xiaoxiao] Washington State Univ, Sch Mech & Mat Engn, POB 642920, Pullman, WA 99164 USA.
通讯机构：
[Liang, Pei] C;[Du, Dan] W;Cent China Normal Univ, Coll Chem, Key Lab Pesticide Chem Biol, Minist Educ, Wuhan 430079, Peoples R China.;Washington State Univ, Sch Mech & Mat Engn, POB 642920, Pullman, WA 99164 USA.
摘要：
We developed a new magnetic nanoparticle sandwich-like immunoassay using protein cage nanoparticles (PCN) for signal amplification together with graphite furnace atomic absorption spectrometry (GFAAS) for the quantification of an organophosphorylated acetylcholinesterase adduct (OP-AChE), the biomarker of exposure to organophosphate pesticides (OPs) and nerve agents. OP-AChE adducts were firstly captured by titanium dioxide coated magnetic nanoparticles (TiO2-MNPs) from the sample matrixes through metal chelation with phospho-moieties, and then selectively recognized by anti-AChE antibody labeled on PCN which was packed with lead phosphate in its cavity (PCN-anti-AChE). The sandwich-like immunoreaction was performed among TiO2-MNPs, OP-AChE and PCN-anti-AChE to form a TiO2-MNP/OP-AChE/PCN-anti-AChE immunocomplex. The complex could be easily isolated from the sample solution with the help of magnet, and the released lead ions from PCN were detected by GFAAS for the quantification of OP-AChE. Greatly enhanced sensitivity was achieved because PCN increased the amount of metal ions in the cavity of each apoferritin. The proposed immunoassay yielded a linear response over a broad range of OP-AChE concentrations from 0.01 nM to 2 nM, with a detection limit of 2 pM, which has enough sensitivity for monitoring of low-dose exposure to OPs. This new method showed an acceptable stability and reproducibility and was validated with OP-AChE spiked human plasma.
作者机构：
[Wen, Lijuan; Kang, Caiyan; Liang, Pei] Cent China Normal Univ, Key Lab Pesticide & Chem Biol, Minist Educ, Coll Chem, Wuhan 430079, Peoples R China.
通讯机构：
[Liang, Pei] C;Cent China Normal Univ, Key Lab Pesticide & Chem Biol, Minist Educ, Coll Chem, Wuhan 430079, Peoples R China.
摘要：
A novel method was developed for the selective determination of lead (Pb) in environmental samples by displacement dispersive liquid-liquid microextraction (D-DLLME) combined with graphite furnace atomic absorption spectrometry (GFAAS). This D-DLLME method involves two steps of dispersive liquid-liquid microextraction (DLLME). Firstly, Zn2+ reacted with diethyldithiocarbamate (DDTC) to form the Zn-DDTC complex and was then extracted with the DLLME procedure. Then the sediment phase was dispersed into the sample solution containing Pb2+ with a dispersive solvent; then another DLLME procedure was carried out. Since the stability of Pb-DDTC is higher than that of Zn-DDTC, Pb2+ can displace Zn2+ from the pre extracted Zn-DDTC complex and be preconcentrated into the sediment phase. The interference from co-existing metal ions with a lower DDTC complex stability was largely eliminated as they cannot displace Zn2+ from the Zn-DDTC complex. Under the optimal conditions, the limit of detection was 35 ng L-1 (3 sigma) for lead, and an enhancement factor of 91 was achieved with a sample volume of 5.0 mL. The proposed method has been successfully applied to the determination of trace lead in environmental samples with satisfactory results.
作者机构：
[Wagner, Elizabeth D.; Jeong, Clara H.; Plewa, Michael J.] Univ Illinois, Dept Crop Sci, Urbana, IL 61801 USA.;[Barcelo, Damia; Postigo, Cristina] Inst Environm Assessment & Water Res IDAEA CSIC, Dept Environm Chem, Water & Soil Qual Res Grp, Barcelona 08034, Barcelona, Spain.;[Richardson, Susan D.] Univ S Carolina, Dept Chem & Biochem, Columbia, SC 29208 USA.;[Simmons, Jane Ellen] US EPA, Natl Hlth & Environm Effects Res Lab, Res Triangle Pk, NC 27709 USA.;[Kimura, Susana Y.; Marinas, Benito J.] Univ Illinois, Dept Civil & Environm Engn, Urbana, IL 61801 USA.
通讯机构：
[Plewa, Michael J.] U;Univ Illinois, Dept Crop Sci, Urbana, IL 61801 USA.
作者机构：
[Yang, Enjian; Yu, Juan; Liang, Pei; Peng, Lili] Cent China Normal Univ, Coll Chem, Key Lab Pesticide & Chem Biol, Minist Educ, Wuhan 430079, Peoples R China.
通讯机构：
[Liang, Pei] C;Cent China Normal Univ, Coll Chem, Key Lab Pesticide & Chem Biol, Minist Educ, Wuhan 430079, Peoples R China.
关键词：
determination;levels;samples
摘要：
A novel and environmentally friendly method has been developed for the determination of lead (Pb) by dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFOD) combined with graphite furnace atomic absorption spectrometry (GFAAS). In this method, 1-undecahol, which is of low density, low toxicity and has a proper melting point near room temperature, was used as the extraction solvent instead of a highly toxic organic solvent, and the phase separation was enhanced by solidification of the floating organic phase. Some parameters influencing the DLLME-SFOD extraction efficiency of Pb and its subsequent determination, such as type and volume of extraction and dispersive solvent, pH of sample solution, concentration of the chelating agent, extraction time and coexisting ions, were systematically investigated. Under the Optimized conditions, the calibration graph exhibited good linearity over the Pb concentration range of 0.05-20.0 ng mL~(-1) with a correlation coefficient (r) of 0.9975. The detection limit of this method for Pb was 18 ng L~(-1) with an enhancement factor of 77, and the relative standard deviation (RSD) was 3.8% at the 1.0 ng mL~(-1) Pb level. The method was successfully applied to the determination of trace amounts of Pb in water samples.
作者机构：
[Liang, Pei; Peng, Lili] Cent China Normal Univ, Key Lab Pesticide & Chem Biol, Minist Educ, Coll Chem, Wuhan 430079, Peoples R China.
通讯机构：
[Liang, Pei] C;Cent China Normal Univ, Key Lab Pesticide & Chem Biol, Minist Educ, Coll Chem, Wuhan 430079, Peoples R China.
摘要：
A novel method based on ionic liquid dispersive liquid-liquid microextraction (IL-DLLME) preconcentration and graphite furnace atomic absorption spectrometry detection was developed for the determination of nickel in lake water, tap water, and seawater samples. In the proposed method, 1-(2-pyridylazo)-2-naphthol (PAN) was used as the chelating agent, acetone as the dispersive solvent, and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) as the extraction solvent instead of a volatile organic solvent. Some parameters influencing the IL-DLLME extraction efficiency of nickel and its subsequent determination, such as the type and volume of IL and dispersive solvent, pH, the amount of PAN, extraction time and centrifuge time, were investigated. Under the optimum conditions, the enrichment factor was 67, the detection limit for nickel was 18 ng L-1 (3 sigma), and the relative standard deviation (RSD) was 6.5% (n=7, c=5.0 ng mL(-1)). The method was successfully applied to the determination of trace amounts of nickel in different water samples.
作者机构：
[Pei Liang; Jinyan Guan] Key Laboratory of Pesticide & Chemical Biology of Ministry of Education, College of Chemistry, Central China Normal University, Wuhan 430079, P.R.China
关键词：
Dispersive solid-phase extraction;solidification of floating organic drop microextraction;HPLC;fungicides
摘要：
A novel approach has been developed for the determination of two fungicides (diethofencarb and pyrimethanil) in fruit juices by dispersive soild-phase extraction (DSPE) followed by solidification of floating organic drop microextraction (SFODME).In the DSPE step, the fungicides were first extracted from fruit juice into acetonitrile, then PSA sorbent was added into the extraction solvent to remove the matrices.After centrifugation, 1.00 mL supematant was used as the dispersive solvent in SFODME.
摘要：
Cloud point extraction was applied as a preconcentration step prior to the determination of cadmium and lead in human teeth samples by inductively coupled plasma optical emission spectrometry (ICP-OES). After complexation with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP), the analytes were quantitatively extracted to and concentrated in the phase rich in the surfactant Triton X-114, then measured by ICP-OES. The parameters affecting the extraction efficiency, such as the pH of the solution, concentration of PMBP and Triton X-114, equilibration temperature and time, were investigated. Using optimum conditions, the detection limits were 0.83 and 1.48 ng for cadmium and lead with relative standard deviations of 2.7% and 3.8%, respectively (n=11). Verification of the accuracy of the method was carried out by analysis of a standard reference material (NIST 1486 Bone Meal). The method was successfully applied to the determination of trace amounts of cadmium and lead in human teeth samples with satisfactory results.
