Determination of cypromazine and its metabolite melamine in milk by cation-selective exhaustive injection and sweeping-capillary micellar electrokinetic chromatography.
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.
College of Science, State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, PR China.
Xuegang
X
Li
Jiwei
J
Hu
Heyou
H
Han
D000818:Animals; D002417:Cattle; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D007306:Insecticides / Q000032:analysis* / Q000378:metabolism*; D008892:Milk / Q000737:chemistry*; D014227:Triazines / Q000032:analysis* / Q000378:metabolism*
D007306:Insecticides; D014227:Triazines; C028704:cyromazine; C011907:melamine