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ABSTRACT: Solid-phase extraction (SPE) and reversed-phase liquid chromatography (RP-LC) have been used for simple, sensitive simultaneous
analysis of cyromazine and melamine residues in liquid milk and eggs. The conditions used for SPE and LC were investigated
and optimized. A combined cation-exchange–reversed-phase cartridge was used for clean-up, and an ODS (C18) column (150mm×4.6mm i.d., 5-μm particles) with 62:38 (v/v) 5mm sodium lauryl sulfate (pH 3.4)–acetonitrile as mobile phase was used for RP-LC. Under the optimum conditions the method limit
of detection (LOD) for both cyromazine and melamine was 6.2μgkg−1 for liquid milk samples, and 11.5μgkg−1 for egg samples. Average recovery of cyromazine and melamine from milk samples was 90.3%, RSD 4.6–5.6%, and 99.6%, RSD 3.2–4.7%,
respectively. Average recovery of cyromazine and melamine from egg samples was 85.3%, RSD 1.0–4.7%, and 89.6%, RSD 3.1–5.0%,
respectively. The method enables detection of melamine and cyromazine at levels as low as 20.7μgkg−1 in liquid milk and 38.3μgkg−1 in egg.
Chromatographia 04/2012; 70(11):1685-1689. · 1.20 Impact Factor
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ABSTRACT: A novel and simple method was, for the first time, developed for effective separation and sensitive detection of cyromazine (CM) and its metabolite melamine (MM) by CZE with DAD (CZE-DAD). Among different solvents, ACN containing 20% NH(4)OH was found to be the best one as an extractant of CM and MM in real samples. After centrifugation and filtering, the extract was analyzed by CZE-DAD directly. The linearity is good in the range of 0.7-50 mg/L with correlation coefficient (r) of 0.9998. Under the optimal conditions, the method LOQ for the two analytes was 0.38 mg/kg for feed samples and 0.42 mg/kg for egg and liquid milk samples. The peaks of MM and CM were identified by comparison of their migration times in real samples with that in standard solution and spiked sample. The effective baseline separation and high sensitivity of MM and CM were achieved. The proposed method has been applied successfully for the quantitative determination of CM and MM residues in real samples. The average total recoveries ranged from 92.5 to 97.4% with the RSD of 3.0-5.1% for CM and from 93.0 to 97.6% with the RSD of 2.8-4.9% for MM. The proposed method offers the effective separation selectivity of CZE as well as a quicker analysis time for simultaneous determination of CM and MM in feed, egg and liquid milk.
Electrophoresis 07/2010; 31(13):2236-41. · 3.30 Impact Factor
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ABSTRACT: A sensitive and selective capillary electrophoresis method is developed, for the first time, for effective separation and simultaneous determination of aminomethylbezoic acid (PAMBA), cefminox sodium (CMNX) and etamsylate (ETM). The electrophoresis conditions were investigated and optimized. A 25 mM phosphate solution (pH 8.5) was used as a buffer and the peak area was determined with UV detection at 216 nm wavelength under 18 kV separation voltage. Under optimal conditions, the three drugs can be separated effectively. Good linearity was achieved in 3.13-150 microg/mL for PAMBA, 6.25-150 microg/mL for CMNX and 3.13-150 microg/mL for ETM, with the correlation coefficients of >0.999. The limit of detection (LOD) for PAMBA, CMNX and ETM was 1.04, 2.08 and 1.04 microg/mL, respectively. Their recoveries in human urine were in the range from 90.2% to 101% with the RSD (n=5) of 0.7-3.1%. The proposed method is simple, rapid and accurate, and provides the sensitivity and linearity necessary for analysis of the test drugs in human urine at clinically relevant concentrations.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 07/2010; 878(21):1899-903. · 2.78 Impact Factor
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ABSTRACT: A novel solid-phase extraction-capillary electrophoresis (SPE-CE) method was developed for the determination of melamine residue in liquid milk. The conditions of SPE and CE were investigated and optimized. A 1% trichloroacetic acid plus 2.2% lead acetate solution were used for the extraction of analyte and the removal of protein. A Cleanert PCX SPE cartridges column was used for clean up. The 50 mM sodium dihydrogenphosphate running buffer (pH adjusted to 3.2 with citric acid) was used as a running buffer. The linearity is satisfactory in the range of 0.8-100 μg/mL with a correlation coefficient of 0.9998. Under the optimal conditions, the method limit of detection (LOD) and method limit of quantification were 0.12 mg/kg and 0.37 mg/kg, respectively. The recovery of melamine from different liquid milk samples was in the range of 89.5-98.5% with a relative standard deviation of 1.8-3.5%. The intra- and inter-day assay precision was 2.8% (n = 6) and 4.1% for five days, respectively. The developed method has been applied successfully for the determination of melamine residue in liquid milk samples. The results obtained by the proposed method agree with those obtained by high-performance liquid chromatographic method. The proposed method enables the quantitative determination of melamine residues at levels as low as 0.37 mg/kg in different liquid milk.
Journal of chromatographic science 01/2010; 48(10):848-53. · 0.88 Impact Factor
