气相色谱-同位素稀释质谱法测定液态乳与乳粉中的三聚氰胺

Determination of Melamine in Raw Milk and Milk Formula by GC-IDMS Method

建立了气相色谱-同位素稀释质谱法测定乳粉和液态乳中三聚氰胺含量的方法。样品加入同位素稀释剂后,经乙腈/水提取,取10mL上清液于Waters Oasis MCX固相萃取柱净化,氮气吹干,70℃衍生化后,进行GC/MS分析,单点法测定。对进样口温度和前处理条件进行了优化研究,并测定了3个液态乳和5个乳粉的实际样品,并对测定结果的不确定度进行了评估。该方法的最小检出限为10μg/kg,原料乳的回收率为95.7%～96.3%,RSD小于4.13%,乳粉中三聚氰胺的回收率为70.2-103.2%,RSD小于6.87%。

The Gas chromatograph-Isotope Dilution Mass Spectrometry method is presented for determination of melamine in milk and milk formula. The sample was extracted by acetonitrile / water and cleaned-up by Waters oasis MCX solid phase extraction cartridges. Extract was analyzed by GC-IDMS with DB5 column after derivated at 70℃ for 1 hour. The inlet temperature and sample preparation process were optimized. 3 milk samples and 5 milk formula samples were analysed and the uncertainties of each result were evaluated. The detection limit of the method is 10μg/kg. The recovery of raw milk is 95.7% -96.3% with RSD〈4.13%. The recovery of milk formula is 70.2-103.2% with RSD〈6.87%.