Abstract:

A method established for determining melamine and creatinine in milk and milk products. The samples were extracted with 1% trichloracetic acid solution. The extract was cleaned-up by using a mixed-mode cation ion exchange SPE column and evaporated to dryness under nitrogen. The residue was derived by bis(trimethylsilyl)trifluoroacetamide-chlorotrimethylsilane (BSTFA-TMCS), then determined by gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Melamine and creatinine had good linearity in the range of 0.1-50 mg/L with the correlation coefficients higher than 0.99, and the limits of quantification were 0.10 mg/kg and 0.20 mg/kg, respectively. The recoveries of melamine and creatinine were 80.7%-116.8% and 77.6%-107.5% with RSD no more than 9.4% and 8.5% in the spiked range of 10-100 mg/kg and 0.1-5.0 mg/kg, respectively. The method is accurate, sensitive, and suitable for the determination of creatinine in milk and milk products.

Key words: creatinine, gas chromatography-mass spectrometry (GC-MS), melamine, milk, milk products