高效液相色谱-串联质谱内标法测定乳品中左旋肉碱含量

Determination of L-Carnitine in Dairy Products by High Performance Liquid Chromatography- Electrospray Ionization Tandem Mass Spectrometry

建立了高效液相色谱-串联质谱内标法测定乳品中左旋肉碱含量的方法。样品经0.1 mol/L HCl溶解,采用乙腈溶液沉淀蛋白,以HILIC色谱柱分离待测物,采用鞘流电喷雾离子化,正离子多反应监测模式（MRM）检测,内标法定量。在3个加标水平下,左旋肉碱的平均加标回收率为85.2%~102.0%,相对标准偏差（RSD,n=6）为7.6%~14.3%,方法检出限（LOD）为50μg/kg,定量下限（LOQ）为200μg/kg。运用该方法对20个乳品样品中的左旋肉碱含量进行测定,检出含量为68~165 mg/kg,与样品标签的符合率达95%。该方法快速、简便、准确,适用于乳品中左旋肉碱含量的测定。

A method of HPLC - MS/MS with internal standard for the determination of L-carnitine in dairy products was developed. After the sample was dissolved in 0. 1 mol/L HC1 solution and its pro- tein was precipitated with acetonitrile, the object was separated with a HILIC chromatographic col- umn, tested by HPLC - MS/MS with sheath flow electro-spray ionization under positive ion scanning and multiple reaction monitoring（MRM） mode, and quantified by the internal standard method. The average recoveries at three spiked levels were in the range of 85.2% - 102.0% with RSDs（ n =6） of 7.6% - 14.3%. The limit of detection （LOD） was 50 μg/kg and the limit of quantitation （ LOQ ） was 200 μg/kg. The proposed method was applied in the analysis of several real samples of different origins from overseas, and 20 samples were screened for L-carnitine with content range of 68 - 165 mg/kg, of which only 1 sample did not match with the label. This method was rapid, simple and accurate, and was suitable for the determining of L-carnitine content in dairy products.