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ABSTRACT: In this study, we described a high-sensitive on-line preconcentration method for cypromazine (CYP) and melamine (MEL) analysis using cation-selective exhaustive injection (CSEI) combined with sweeping-MEKC. The optimum conditions of on-line concentration and separation were discussed. The BGE contained 100 mM SDS, 50 mM phosphoric acid (pH=2.0) and 15% acetonitrile (v/v). The sample was injected at 10 kV for 600 s, separated at -20 kV, and detected at 210 nm. The sensitivity enhancements were 6222 for CYP and 9179 for MEL. The linear dynamic ranges were 0.4-25 ng/mL for CYP (r=0.9995) and 0.2-12 ng/mL for MEL (r=0.9991). The LODs (signal-to-noise ratio, 3) were 43.7 and 23.4 pg/mL for CYP and MEL, respectively. The proposed method was applied to analyze CYP and MEL in dairy products pretreated using off-line SPE to minimize the influence of the matrix. The recoveries of CYP and MEL were satisfactory (ca. 74-83%). The experimental results suggest that the CSEI-sweeping-MEKC method is feasible for the application to simultaneously detect trace levels of CYP and its metabolite MEL in real milk samples.
Journal of Separation Science 02/2011; 34(3):323-30. · 2.73 Impact Factor
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ABSTRACT: On-line concentration techniques in capillary electrophoresis, including stacking and sweeping, have a weak tolerance towards complex real samples. A phenyl-functionalized hybrid silica monolithic polymeric capillary column (id 530 microm) was prepared by in-situ co-condensation of phenyltriethoxysilane (PTES) and tetraethoxysilane (TEOS). In order to enhance the stability of a monolithic column within a wide-bore capillary, a novel and simple frit-preparation method for wide-bore capillaries was first introduced by immobilizing a short length of capillary of suitable outer diameter at the end of the monolithic capillary column during condensation of the sol-gel solution. The monolithic column was used for the extraction of bisphenol A (BPA) from cola samples, and the interfering compounds can be removed from the samples with 40% ACN solution (v/v) as eluent. The pretreated samples were further concentrated and separated using large-volume stacking and sweeping micellar electrokinetic chromatography. The method was successfully applied to the determination of bisphenol A spiked in cola, yielding a detection limit of 1.8 ng/mL. Close correlation coefficients and acceptable method reproducibility were obtained for bisphenol A over a linear range of 0.005-0.200 microg/mL.
Journal of Separation Science 08/2009; 32(15-16):2759-66. · 2.73 Impact Factor
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ABSTRACT: The post-chemiluminescence (PCL) reaction was observed with the mixture solution after completion CL reaction of luminol-H 2 O 2 in present of Furazolidone (FZD). A novel method for the determination of FZD was established by flow-injection PCL. The CL intensity responded linearly to the concentration of FZD in the range 1.0×10 −7 -1.0×10 −5 g mL -1 , with a linear correlation of 0.9949. The detection limit for FZD was 1.96×10 −8 g mL -1 (S/N=3). The relative standard deviation (RSD) was 3.5% (n=11, c=1.0×10 −6 g mL -1). The proposed method has been applied to the determination of FZD in animal feeds and the results were consistent with those obtained by the HPLC-UV method. A possible mechanism for the PCL reaction was also discussed by the investigation of CL kinetic characteristics, CL spectra and UV-Vis absorption spectra.
Am. J. Biomed. Sci. 2009(1):260-266.
