Chengjun Wang

Nankai University, Tianjin, Tianjin Shi, China

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Publications (12)28.72 Total impact

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    ABSTRACT: A dispersive multiwalled carbon nanotubes (MWCNTs) based agitation-assisted adsorption and ultrasound-assisted desorption method has been developed for extracting natural estrogenic steroids in environmental waters prior to high performance liquid chromatography-diode array detection (HPLC-DAD) analysis. With the aid of agitation, the trace estrogens in bulk aqueous solution were adsorbed onto the milligrams of dispersive MWCNTs. After filtration, the estrogens enriched on MWCNTs nanoparticles were quickly desorbed into milliliters of organic solvent in ultrasonic bath. Finally, the analytes in organic solvent were directly determined by HPLC-DAD. The stability examination of estrogens under the tested ultrasonic irradiation was performed and the results indicated that the estrogens were stable during the extraction process. Several parameters that could influence the extraction efficiency, such as type and volume of desorption solvent, consumed amount of MWCNTs, pH and ionic strength of sample solution, agitation-assisted adsorption and ultrasound-assisted desorption time, were examined. Under the optimized conditions, the recoveries for three analytes in spiked samples were over 82%. The detection limits were 0.076 ng mL-1 for estrone, 0.049 ng mL-1 for 17!-estradiol, and 0.057 ng mL-1 for estriol, respectively, while the relative standard deviations were less than 9% (at 20 ng mL-1 estrogens level for 10 runs).
    Analytical methods 01/2014; · 1.86 Impact Factor
  • Xuejiao Tang, Lili Li, Boxiong Shen, Chengjun Wang
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    ABSTRACT: The FeNi alloy nanoparticles (FeNi and BFeNi) supported on natural halloysite nanotubes (HNTs) were prepared for catalytic decomposition of toxic phosphine (PH3) to yellow phosphorus and hydrogen. The Fourier transform infrared spectroscopy, X-ray diffraction, inductively coupled plasma, scanning electron microscope, and hydrogen temperature-programmed reduction tests were carried out to characterize the physicochemical properties of HNTs and the prepared nano-catalysts. Nearly 100% PH3 was decomposed into yellow phosphorus and hydrogen at 420°C with prepared FeNi/HNTs catalysts. Metallic Ni and Fe3O4 could be the catalytic active sites in FeNi/HNTs for PH3 decomposition under the low temperature. The boron (B) additives decrease the catalytic activity of FeNi/HNTs for PH3 decomposition due to the formation of the spinal NiFe2O4 and Fe2B which replace the active Fe3O4 and metallic Ni in catalysts. The developed FeNi/HNTs are low-cost and effective catalysts for air-pollution control and recycle of the hazardous waste PH3 gas in industry.
    Chemosphere 03/2013; · 3.14 Impact Factor
  • Xixi Song, Mingde Ye, Xuejiao Tang, Chengjun Wang
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    ABSTRACT: An ionic liquid (IL) based dispersive liquid-liquid microextraction combined with HPLC hydride generation atomic fluorescence spectrometry method for the preconcentration and determination of mercury species in environmental water samples is described. Four mercury species (MeHg(+) , EtHg(+) , PhHg(+) , and Hg(2+) ) were complexed with dithionate and the neutral chelates were extracted into IL drops using dispersive liquid-liquid microextraction. Variables affecting the formation and extraction of mercury dithizonates were optimized. The optimum conditions found were as follows: IL-type and amount, 0.05 g of 1-octyl-3-methylimidazolium hexafluorophosphate; dispersive solvents type and amount, 500 μL of acetone; pH, 6; extraction time, 2 min; centrifugation time, 12 min; and no sodium chloride addition. Under the optimized conditions, the detection limits of the analytes were 0.031 μg/L for Hg(2+) , 0.016 μg/L for MeHg(+) , 0.024 μg/L for EtHg(+) , and 0.092 μg/L for PhHg(+) , respectively. The repeatability of the method, expressed as RSD, was between 1.4 and 5.2% (n = 10), and the average recoveries for spiked test were 96.9% for Hg(2+) , 90.9% for MeHg(+) , 90.5% for EtHg(+) , 92.3% for PhHg(+) , respectively. The developed method was successfully applied for the speciation of mercury in environmental water samples.
    Journal of Separation Science 12/2012; · 2.59 Impact Factor
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    ABSTRACT: A novel, simple and rapid method, termed ultrasound-assisted emulsification microextraction and solidification of floating organic droplet (UAEM-SFO) coupled to high performance capillary electrophoresis (HPCE), was developed for preconcentration and analysis of five phenolic compounds (PCs) in human urine and blood samples. The proposed method is based on microextraction of target analytes in less-toxic organic solvent under assistance of ultrasound. A micro-droplet of less-toxic organic solvent floating on the surface of liquid samples in a sealed vial can be dispersed into sample solutions under the ultrasound frequency, solidified under ice bath, collected with a medicine spatula, molten at ambient temperature, and finally subjected to HPCE analysis. The parameters of UAEM-SFO procedure including type and volume of extraction solvent, extraction temperature, time of ultrasound-assisted extraction and centrifugation, sample pH, and ionic strength were optimized. The influence parameters on HPCE resolution such as pH, concentration of running buffer, applied voltage and injection time were also investigated. This method requires only 40 μL of 2-dodecanol extraction solvent and 8 min of pretreatment time. The enrichment factors of analytes were in the range of 114-172 and extraction recoveries (69-86%) were obtained. Good linearity was achieved for five analytes in the range of 0.05-100 μg L⁻¹ and the correlation coefficients ranged from 0.9934 to 0.9999. The limits of detection were 0.01 μg L⁻¹ for triclosan (TCS) and biophenol A (BPA), and 0.02 μg L⁻¹ for pentachlorophenol (PCP), 2,4-dichlorophenol (2,4-DCP) and 4-nonylphenol (4-NP) in urine samples, and 0.02 μg L⁻¹ for TCS and BPA, 0.04 μg L⁻¹ for PCP, 2,4-DCP and 4-NP in blood samples. The developed UAEM-SFO-HPCE method has a great potential in routine residual analysis of trace PCs in biological samples.
    Journal of Chromatography A 07/2012; 1253:16-21. · 4.61 Impact Factor
  • Zhiling Li, Fan Chen, Xuedong Wang, Chengjun Wang
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    ABSTRACT: An environmentally friendly ionic liquids dispersive liquid-liquid microextraction (IL-DLLME) method coupled with high-performance liquid chromatography (HPLC) for the determination of antihypertensive drugs irbesartan and valsartan in human urine samples was developed. The HPLC separations were accomplished in less than 10 min using a reversed-phase C(18) column (250 × 4.60 mm i.d., 5 µm) with a mobile phase containing 0.3 % formic acid solution and methanol (v/v, 3:7; flow rate, 1.0 mL/min). UV absorption responses at 236 nm were linear over a wide concentration range from 50 µg/mL to the detection limits of 3.3 µg/L for valsartan and 1.5 µg/L for irbesartan. The effective parameters on IL-DLLME, such as ionic liquid types and their amounts, disperser solvent types and their volume, pH of the sample and extraction time were studied and optimized. The developed IL-DLLME-HPLC was successfully applied for evaluation of the urine irbesartan and valsartan profile following oral capsules administration. Copyright © 2012 John Wiley & Sons, Ltd.
    Biomedical Chromatography 06/2012; · 1.95 Impact Factor
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    ABSTRACT: A high-performance liquid chromatography coupled with photodiode-array spectrophotometry and electrospray ionization-mass spectrometry (HPLC-PDA-ESI-MS) method for separation and determination of phenolic acids in ethyl acetate extracts from Chinese waxberry (Myrica Rubra) juice was developed. Total of 4 phenolic acids (ferulic, caffeic, sinapic, and salicylic acids) were identified by comparing their HPLC retention times, UV-Vis absorption spectra, and simultaneously recorded mass spectra with authentic standards. Quantitation was carried out by the peak area method. The calibration curves are linear over the concentration range studied with the correlation coefficients, R(2), greater than 0.99. The contents of ferulic, caffeic, sinapic, and salicylic acids in waxberry juice samples studied were 2.76, 3.58, 2.89, and 1.92 mg/L, respectively, and they occur mainly in bound forms. All relative standard deviations were less than 4%. The recoveries range from 83.6% to 95.8% for the 4 analytes. To the authors' best knowledge, this is the first report for the identification of the sinapic and salicylic acids in Chinese waxberry products.
    Journal of Food Science 02/2012; 77(2):C272-7. · 1.78 Impact Factor
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    ABSTRACT: The effects of 12 imidazolium room temperature ionic liquids (RTILs), including [C(n) mim]BF(4) , [C(n) mim]PF(6) , and [C(n) mim]Br (n = 4, 6, 8, 10), on the fluorescent properties of norfloxacin were examined. The fluorescence intensity of norfloxacin at 0.1 mg/L in methanol significantly increased with the addition of [C(n) mim]BF(4) and [C(n) mim]PF(6) into the solvent at 0.1-15.0%. The sensitizing effect may result from the higher viscosity of the RTILs-methanol mixture solvent than that of the methanol itself. However, the quenching effect on fluorescence of norfloxacin was observed in [C(n) mim]Br-methanol solvent. The fluorescence intensities of norfloxacin decreased with an increase in the alkyl chain length of the alkyl substituents of the imidazolium ring of RTILs. The main interaction between the RTILs and norfloxacin is not by hydrogen bonding. The fact, that some RTILs can significantly sensitize fluorescence of norfloxacin, indicates that RTILs could be a group of promising solvents for development of sensitive spectrofluorimetric methods for determination of norfloxacin at ultra-trace levels in environmental samples. Copyright © 2011 John Wiley & Sons, Ltd.
    Luminescence 12/2011; · 1.27 Impact Factor
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    ABSTRACT: Influences of one sewage sludge on degradation of hexazinone and formation of its major metabolites were investigated in four forest soils (A, B, C and D), collected in Zhejiang Province, China. In non-amended forest soils, the degradation half-life of hexazinone was 21.4, 30.4, 19.4 and 32.8 days in forest soil A, B, C and D, respectively. Degradation could start in soil A and C without lag period because the two soils had been contaminated by this herbicide for a long time, possibly leading to completion of acclimation period of hexazinone-degrading bacteria. In forest soils amended with sewage sludge, the degradation rate constant increased by 17.3% in soil A, 48.2% in soil B, 8.1% in soil C and 51.6% in soil D, respectively. The higher degradation rates (soil A and C) in non-amended soils accord with the lower rate increase in sewage sludge-amended soils. Under non-sterile conditions, biological mechanism accounted for 51.8-62.4% of hexazinone degradation in four soils. Under sterile conditions, the four soils had the similar chemical degradation capacity for hexazinone. In non-amended soil B, only one metabolite (B) was detected, while two metabolites (B and C) were found in sewage sludge-amended soil B. Similarly situated in agricultural soils, N-demethylation at 6-position of triazine ring, hydroxylation at the 4-positon of cyclohexyl group, and removal of the dimethylamino group with formation of a carbonyl group at 6-position of triazine ring appear to be the principal mechanism involved in hexazinone degradation in sewage sludge-amended forest soils. These data will improve understanding of the actual pollution risk as a result of forest soil fertilization with sewage sludge.
    Journal of hazardous materials 11/2011; 199-200:96-104. · 4.14 Impact Factor
  • Chengjun Wang, Chunmei Xu, Fan Chen, Xuejiao Tang
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    ABSTRACT: A simple, sensitive and accurate reversed-phase high-performance liquid chromatographic (HPLC) method for simultaneous determination of three naturally occurring estrogenic steroids including estrone (E1), 17β-estradiol (E2) and estriol (E3) in environmental water samples was developed. Analytes were extracted with ethyl acetate solvents and preconcentrated prior to HPLC analysis. Separations were accomplished in <20 min using a reversed-phase C(18) column (4.6×250 mm id, 5 μm) with a gradient elution of mobile phase containing 3.0 mM ammonium acetate/acetonitrile mixtures (flow rate, 1.0 mL/min). UV light absorption responses at 205 nm were linear over a wide concentration range from 100,000 μg/L to the detection limits of 0.96 μg/L E1, 0.64 μg/L E2 and 0.78 μg/L E3. Quantitation was carried out by the peak area method. The relative standard deviation for the analysis of three estrogens was <3.0%. This method was applied for the simultaneous determination of estrogens in environmental water samples collected in Zhejiang, China. The higher concentrations of both E2 and E3 were found in Tang River and West Lake waters, and E1 was detected in lake water only. All three estrogens were below the detection limits in rain waters.
    Journal of Separation Science 07/2011; 34(18):2371-5. · 2.59 Impact Factor
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    ABSTRACT: An effective multi-residue pretreatment technique, solid-phase extraction (SPE) combined with dispersive liquid-liquid microextraction (DLLME), was proposed for the trace analysis of 14 polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in milk samples using gas chromatography-mass spectrometry (GC-MS). Interesting analytes in milk samples were extracted with hexane after protein precipitation. The hexane extracts were loaded on an LC-Florisil column to isolate analytes from the milk matrix. The elutes were dried and dissolved in acetone, which was used as the disperser solvent in subsequent DLLME procedures. The effects of several important parameters on the extraction efficiency were evaluated. Under the optimized conditions, a linear relationship was obtained in the range of 0.02-10.00 μg/L (PCBs) and 0.5-100.00 μg/L (PBDEs). The LOD (S/N=3) and relative standard deviations (RSDs, n=5) for all analytes were 0.01-0.4 μg/L and 0.6-8.5%, respectively. The recoveries of the standards added to raw bovine milk samples were 74.0-131.8%, and the repeatabilities of the analysis results were 1.12-17.41%. This method has been successfully applied to estimating PCBs and PBDEs in milk samples.
    Journal of Separation Science 03/2011; 34(9):1084-90. · 2.59 Impact Factor
  • Huili Wang, Chengjun Wang, Fan Chen, Xuedong Wang
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    ABSTRACT: Degradation of Chlorothalonil (CTN) was investigated in four different paddy soils under anaerobic conditions. The CTN biodegradation is strongly affected by the properties of the paddy soils. Soils associating with rich total carbon (TC), repeated CTN application, and neutral pH have shown the high capacity to biodegrade CTN. Additionally, anaerobic CTN biodegradation was accompanied by the methane generation and a drop of oxidation-reduction potential (ORP). The initial CTN concentration had a significant effect on CTN removal efficiency, and increase in the initial CTN concentration resulted in the decreasing of CTN removal percentage. However, it is believed that the inhibitory effect on anaerobic biodegradation of CTN is negligible in natural environment due to the much lower concentration of CTN in natural environment (at ng g(-1) or pg g(-1) level) than the one (10 μg g(-1)) investigated in this study. The 4-hydroxy-2,5,6- trichloroisophthalonitrile (HTI), one of the major metabolites of CTN degradation, has shown the significant inhibitation to the anaerobic CTN biodegradation when its residual level is over 0.1 μg g(-1).
    Ecotoxicology and Environmental Safety 03/2011; 74(4):1000-5. · 2.20 Impact Factor
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    ABSTRACT: Direct electroless metallization on acrylonitrile–butadiene–styrene (ABS) plastic with Pd-free activation method could reduce the cost of production. A novel surface activation method with the immobilization of Ni(0) nanoparticles by chitosan (CTS) film on ABS and then the deposition of Ni and Au on ABS were investigated in this paper. X-ray photoelectron spectroscopy (XPS), fourier transform infrared (FTIR) spectra and scanning electron microscopy (SEM) data revealed the related interfacial reaction mechanism in activation process. The Ni(0) nanoparticles immobilized by the CTS films were effective auto-catalysts in the nickel electroless plating process. The formations of Ni plating layers at different deposition time were observed by SEM. The x-ray diffraction (XRD) patterns revealed the Ni layer at 30min was in an amorphous phase. Au was successfully plated on the Ni layers in a new, stable non-cyanide Au electroless plating bath with different reducing agents. The chemical compositions of Ni/Au layers were analyzed by inductive couple plasmas (ICP) and ion chromatography (IC) measurements. Inorganic element (P or S) from reducing agents made the surface morphology of Au layers different in SEM images. However, they did not change the Au crystallization phase at all based on XRD patterns.
    Surface & Coatings Technology - SURF COAT TECH. 01/2011; 206(6):1382-1388.

Publication Stats

26 Citations
28.72 Total Impact Points

Institutions

  • 2013
    • Nankai University
      • College of Environmental Science and Engineering
      Tianjin, Tianjin Shi, China
  • 2011–2013
    • Wenzhou University
      Yung-chia, Zhejiang Sheng, China
  • 2011–2012
    • Wenzhou Medical College
      • • School of Life Sciences
      • • School of Environmental Science and Public Health
      Wenzhou, Zhejiang Sheng, China