A multi-laboratory study was conducted on AOAC First Action Method 2015.10 “Determination of Free and Total Choline and Free and Total Carnitine in Infant Formula and Adult/Pediatric Nutritional Formula by Liquid Chromatography/Tandem Mass Spectrometry (HPLC-MS/MS).” In this study, nine laboratories participated in the performance testing of the method using 10 nutritional products tested as blind duplicates. Both free and total carnitine and free and total choline content of the samples were determined using separate extractions for the free and total results. For free choline and carnitine analysis, samples are diluted in water. For total choline and carnitine analysis, samples are extracted using acid assisted microwave hydrolysis with nitric acid. For both the free and total methods, samples are then diluted with acetonitrile and analyzed using strong cation exchange (SCX) liquid chromatography coupled to a triple quadrupole tandem mass spectrometer (LCMS). Stable isotope labeled internal standards were utilized in all analyses to compensate for extraction inefficiencies and ionization suppression.

中文翻译：

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液相色谱/串联质谱 (HPLC-MS/MS) 测定婴儿配方食品和成人/儿童营养配方食品中的游离和总胆碱以及游离和总肉碱：一项多实验室测试研究，最终行动 2015.10

对 AOAC First Action Method 进行了多实验室研究2015.10“通过液相色谱/串联质谱 (HPLC-MS/MS) 测定婴儿配方食品和成人/儿童营养配方食品中的游离和总胆碱以及游离和总肉碱。” 在这项研究中，九个实验室参与了该方法的性能测试，使用了 10 种作为盲法测试的营养产品。样品的游离和总肉碱以及游离和总胆碱含量均使用单独的提取来确定游离和总结果。对于游离胆碱和肉毒碱分析，样品在水中稀释。对于总胆碱和肉毒碱分析，使用硝酸的酸辅助微波水解提取样品。对于 free 和 total 方法，然后用乙腈稀释样品，并使用与三重四极杆串联质谱仪 (LCMS) 耦合的强阳离子交换 (SCX) 液相色谱进行分析。在所有分析中都使用了稳定同位素标记的内标，以补偿萃取效率低下和电离抑制。