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ABSTRACT: The organophosphorus pesticides including phorate, diazinon, tolclofos-methyl, fenitrothin, malathion, fenthion, isocarbophos, quinalphos and phenamiphos, in peanut oils were determined by liquid-liquid extraction coupled with dispersive solid phase extraction and gas chromatography-mass spectrometry (GC-MS). The mixture of multi-walled carbon nanotubes and alumina was used as adsorbent in dispersive solid phase extraction. The effects of some experimental conditions, such as types of multi-walled carbon nanotubes, amount of adsorbents and extraction time were examined. The limits of detection for the analytes were between 0.7 and 1.6 μg kg(-1). The obtained recoveries of the analytes in the samples were between 85.9 and 114.3% and relative standard deviations were lower than 8.48%.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 09/2011; 879(30):3423-8. · 2.78 Impact Factor
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ABSTRACT: The multiwall carbon nanotubes (MWCNTs)-based matrix solid phase dispersion (MSPD) was applied for the extraction of hormones, including 17-α-ethinylestradiol, 17-α-estradiol, estriol, 17-β-estradiol, estrone, medroxyprogesterone, progesterone and norethisterone acetate in butter samples. The method includes MSPD extraction of the target analytes from butter samples, derivatization of hormones with heptafluorobutyric acid anhydride-acetonitrile mixture, and determination by gas chromatography-mass spectrometry. The mixture containing 0.30 g graphitized MWCNTs and 0.10 g MWCNTs was selected as absorbent. Ethyl acetate was used as elution solvent. The elution solvent volume and flow rate were 12 mL and 0.9 mL min(-1), respectively. The recoveries of hormones obtained by analyzing the five spiked butter samples were from 84.5 to 111.2% and relative standard deviations from 1.9 to 8.9%. Limits of detection and quantification for determining the analytes were in the range of 0.2-1.3 and 0.8-4.5 μg kg(-1), respectively. Compared with other traditional methods, the proposed method is simpler in the operation and shorter in the sample pretreatment time.
Journal of chromatography. A 06/2011; 1218(31):5047-54. · 4.19 Impact Factor
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ABSTRACT: A wavelength modulation surface plasmon resonance biosensor based on ZnO-Au nanocomposites for the detection of human IgM was developed. Self-assembly technique has the advantages of flexibility, simplicity and the precise control of film component and was applied to the building of the sensor. The ZnO-Au nanocomposites are in a dumbbell-like shape and can be immobilized on the Au film through 1,6-hexanedithiol by covalent attachment. Meanwhile the activated ZnO nanocrystals can be used to connect protein. The biosensor based on ZnO-Au nanocomposites was used to detect human IgM. Some experimental conditions were examined and optimized. In the selected conditions, the modified biosensor exhibits a satisfactory response for human IgM in the concentration range of 0.30-20.00 microg mL(-1). However, the biosensor without ZnO-Au nanocomposites shows a response for human IgM in the concentration range of 1.25-20.00 microg mL(-1). Compared with the biosensor based on Au film, when the biosensor based on the ZnO-Au nanocomposites was applied, the sensitivity for determination of human IgM is significantly enhanced.
Analytica chimica acta 10/2009; 653(1):109-15. · 4.31 Impact Factor
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ABSTRACT: A novel surface plasmon resonance (SPR) biosensor for the determination of human IgG was introduced. The biosensor was prepared with three layers of titania sol-gel membrane by vapor deposition. The colloid Au nanoparticle (AuNP) was immobilized in the second layer of titania membrane and the AuNP coupled with rabbit anti-human IgG was encapsulated in the third layer. The AuNP in the second layer of titania membrane was proved to be effective in the sensitivity enhancement of SPR biosensor. The lowest concentration that could be detected obtained by the biosensor with AuNP is about eight times lower than that obtained without AuNP. In addition, the titania sol-gel is a porous homogeneous material that permits analytes to access the encapsulated biomolecule and can provide a controlled environment for the study of biomolecular recognition. The titania sol-gel was also confirmed to be benefit for biomolecule to keep bioactivity, which could offer a good waterish microenvironment. As a result, the modified biosensor exhibits a satisfactory response for human IgG in the concentration range of 0.30-40.00 microg mL(-1) and shows favorable bioactivity for a long time.
Colloids and surfaces. B, Biointerfaces 09/2009; 75(2):520-5. · 2.60 Impact Factor
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ABSTRACT: Based on well-known silver mirror reaction the Ag film was formed on Au film modified by self-assembled monolayer (SAM) of 1,6-hexanedithiol (HDT). The sensitivity of the biosensor based on this Ag/Au film is enhanced compared to that based on Au film. When the surface plasmon resonance (SPR) biosensor based on this Ag/Au film was used to determine human IgG, the range of concentrations of human IgG that could be determined is 0.30-40.00 microg mL(-1). The lowest concentration (0.30 microg mL(-1)) that could be detected was about 8 times lower than that obtained by the biosensor without modification by Ag film (2.50 microg mL(-1)), which demonstrated that the biosensor based on Ag/Au film could make the resonant wavelength move to longer wavelength following with the sensitivity enhancement of the SPR biosensor.
Talanta 05/2009; 78(1):265-9. · 3.79 Impact Factor
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ABSTRACT: An unique miniature simultaneous microwave plasma torch (MPT) atomic emission spectrometer employing linear UV intensified charge-coupled device (ICCD) array detector has been developed and studied preliminarily. The detection limits and precisions of the spectrometer for Ag, Al, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Sr and V by using different CCD exposure times have been determined. An analysis of a practical sample has been carried out. The preliminary results demonstrate that such simultaneous spectrometer has advantages of saving sample and time, especially suitable for use as detector for chromatography and in combination with flow injection systems. Taking analytical figures of merit and portability into accounts, the miniature simultaneous MPT system will have extended application areas and greater competition potential as compared with commercialized scanning MPT spectrometers.
Microchemical Journal.
