Abstract:

A gas chromatography tandem triple quadrupole mass spectrometric (GC-QqQ-MS/MS) method was presented for the determination of cyanuric acid and melamine in milk powder. Samples were extracted with methanol and derivatized with a mixed system composed of BSTFA and TMCS (99:1, V/V) prior to GC-QqQ-MS/MS analysis in multiple reaction monitoring (MRM) mode. The optimal values of crucial instrument parameters and matrix effects were investigated. Cyanuric acid was qualified using the ion pairs of m/z 345 > 215 and m/z 345 > 330 and quantified using the ion pair of m/z 345 > 215. Melamine was qualified using the ion pairs of m/z 345 > 171 and m/z 342 > 327 and quantified using the ion pair of m/z 342 > 327. The developed method exhibited good linearity within the range of 0.010 to 0.500 mg/L. Limit of detection was 0.016 for cyanuric acid and 0.003 mg/kg for melamine (RSN =3). Precision RSDs for determining cyanuric acid and melamine were within the ranges of 4.5%－8.6% and 3.9%－6.2%, respectively. Recoveries of cyanuric acid and melamine in an infant formula milk power sample spiked at two levels were ranged from 84.0% to 102.0% and from 88.5% to 104.0%, respectively.

Key words: gas chromatography tandem triple quadruple mass spectrometry (GC-QqQ-MS/MS), multiple reaction monitoring (MRM) mode, derivatization, milk powder, cyanuric acid, melamine