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Li Z.-A.,Sichuan University | Tan Q.,Chengdu Environmental Monitoring Center | Hou X.,Sichuan University | Hou X.,University of Sichuan | And 2 more authors.
Analytical Chemistry | Year: 2014

A simple and sensitive approach is proposed and evaluated for determination of ultratrace Zn and Cd in limited amounts of samples or tens of cells based on a novel single drop (5-20 μL) solution electrode glow discharge assisted-chemical vapor generation technique. Volatile species of Zn and Cd were immediately generated and separated from the liquid phase for transporting to atomic fluorescence or atomic mass spectrometric detectors for their determination only using hydrogen when the glow discharge was ignited between the surface of a liquid drop and the tip of a tungsten electrode. Limits of detection are better than 0.01 μg L-1 (0.2 pg) for Cd and 0.1 μg L-1 (2 pg) for Zn, respectively, and comparable or better than the previously reported results due to only a 20 μL sampling volume required, which makes the proposed technique convenient for the determination of Zn and Cd in limited amounts of samples or even only tens of cells. The proposed method not only retains the advantages of conventional chemical vapor generation but also provides several unique advantages, including better sensitivity, lower sample and power consumption, higher chemical vapor generation efficiencies and simpler setup, as well as greener analytical chemistry. The utility of this technique was demonstrated by the determination of ultratrace Cd and Zn in several single human hair samples, Certified Reference Materials GBW07601a (human hair powder) and paramecium cells. (Graph Presented). © 2014 American Chemical Society. Source

Sun Y.,University of Sichuan | Liu J.,Chengdu Environmental Monitoring Center | Xie T.,University of Sichuan | Xiong X.,University of Sichuan | And 3 more authors.
Energy and Fuels | Year: 2014

A large amount of crude glycerol is generated during biodiesel production, but it has little commercial value. In this study, glycerol was used to cultivate Chlorella vulgaris to recycle its surplus, and its effects on microalgal growth and lipid accumulation were investigated. Lipid production in glycerol batch culture was higher than in glucose batch culture. However, the cell growth was slow, and a lag phase was more obvious as glycerol concentration increased from 1 to 30 g L-1. A two-stage fed-batch culture was developed to achieve high cell density and lipid production in C. vulgaris. In this culture, high microalgal cell concentration was first obtained by glucose, and lipid accumulation was enhanced by later additions of crude glycerol. Lipid production and lipid content reached 1663.02 mg L-1 and 36.39%, respectively. Lipids produced by C. vulgaris were good feedstock for biodiesel production. © 2014 American Chemical Society. Source

Hou X.,University of Sichuan | Hou X.,Chengdu Environmental Monitoring Center | Ai X.,University of Sichuan | Jiang X.,University of Sichuan | And 3 more authors.
Analyst | Year: 2012

A new, miniaturized and low power consumption photochemical vapor generation (PVG) technique utilizing an ultraviolet light-emitting diode (UV-LED) lamp is described, and further validated via the determination of trace mercury. In the presence of formic acid, the mercury cold vapor is favourably generated from Hg 2+ solutions by UV-LED irradiation, and then rapidly transported to an atomic fluorescence spectrometer for detection. Optimum conditions for PVG and interferences from concomitant elements were investigated in detail. Under optimum conditions, a limit of detection (LOD) of 0.01 μg L -1 was obtained, and the precision was better than 3.2% (n = 11, RSD) at 1 μg L -1 Hg 2+. No obvious interferences from any common ions were evident. The methodology was successfully applied to the determination of mercury in National Research Council Canada DORM-3 fish muscle tissue and several water samples. © 2012 The Royal Society of Chemistry. Source

Liu Y.,Sichuan Agricultural University | Liu Y.,Chengdu Environmental Monitoring Center | Lin L.,Yaan Soil and Water Conservation Monitoring Substation | Jin Q.,Sichuan Agricultural University | Zhu X.,Sichuan Agricultural University
Environmental Progress and Sustainable Energy | Year: 2015

Advances in phytoremediation research require the selection of new hyperaccumulators or accumulators and investigations of their tolerance and accumulation of heavy metals. Two concentration gradient experiments (preliminary and verification), involving the same soil Cd concentrations (0, 25, 50, 75, 100, and 125 mg kg-1), were conducted to study Cd accumulation and tolerance in Capsella bursa-pastoris. In the preliminary and verification concentration gradient experiments, the Cd content in shoots of C. bursa-pastoris exceeded 100 mg kg-1 at a soil Cd concentration of 50 mg kg-1, and the maxima of Cd contents in shoots were 307.67 and 369.20 mg kg-1 at 125 mg kg-1 Cd in soil, respectively. The shoot bioconcentration factor of C. bursa-pastoris was greater than 1, but the translocation factor was less than 1.0 in the preliminary and verification concentration gradient experiments. In the verification concentration gradient experiment, the malondialdehyde content and the activities of superoxide dismutase, peroxidase, and catalase increased compared with the control. Therefore, C. bursa-pastoris is a Cd-accumulator with strong tolerance to Cd, and could be used to remediate Cd-contaminated farmland soil in winter. © 2014 American Institute of Chemical Engineers Environ Prog. Source

Leng G.,University of Sichuan | Yin H.,Chengdu Environmental Monitoring Center | Li S.,University of Sichuan | Chen Y.,Chengdu Environmental Monitoring Center | Dan D.,University of Sichuan
Talanta | Year: 2012

A simple and fast solvent microextraction method termed vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography-vapor generation atomic fluorescence spectrometry (HPLC-CVAFS) has been developed for the trace analysis of methylmercury (MeHg), ethylmercury (EtHg) and inorganic mercury (Hg2) in sediment samples. Carbon tetrachloride was used as collecting solvent for the extraction of mercury species from sediment by a vortex-assisted extraction. In VALLME, 100 μL 1% (m/v) l-Cysteine were used as extraction solvent and were injected into 4 mL carbon tetrachloride. The extraction solvent dispersed into carbon tetrachloride under vigorously shaking by a vortex agitator. The fine droplets could extract mercury species within few minutes because of the shorter diffusion distance and larger specific surface area. After centrifugation, the floating extractant phase restored its initial single microdrop shape and was used for HPLC-CVAFS analysis. The parameters affecting the extraction efficiency of the proposed VALLME such as extraction solvent, vortex time, volumes of extraction solvent and salt addition etc. were investigated. Under the optimum conditions, linearity was found in the concentration range from 0.1 to 25 ng g-1 for MeHg, 0.2 to 65 ng g-1 for EtHg, and 0.1 to 30 ng g-1 for Hg2. Coefficients of determination (R2) ranged from 0.9938 to 0.9972. The limits of detection (LODs, signal-to-noise ratio (S/N)=3) were 0.028 ng g-1 for MeHg, 0.057 ng g-1 for EtHg, and 0.029 ng g-1 for Hg2. Reproducibility and recoveries were assessed by testing a series of 6 sediment samples, which were spiked with different concentration levels. Finally, the proposed method was successfully applied in analyses of real nature sediment samples. In this work, VALLME was applied to the extraction of mercury species in sediment samples for the first time. Using l-Cys as extraction solvent, the extraction process is sensitive and environmentally friendly and could be achieved within 3 min. © 2012 Elsevier B.V. Source

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