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Abstract：
Current analytical methods for amino acid (AA) analysis in ruminant nutrition are time-consuming and expensive. This study aimed to develop a method for AA analysis that is faster, more efficient, rugged, and accessible. Four representative matrixes were selected for method development and validation: milk, tissue, feed, and soy flour standard reference material from National Institute of Standards and Technology. Acid and alkaline hydrolysis were used to analyze 18 AA. Separation of AA was performed using a Z-HILIC column in an 18-min run coupled to a triple quadrupole LC/MS system in positive and negative electrospray ionization for identification and quantitation. The method was evaluated for recovery, precision, calibration curve linearity, and limits of detection (LODs) and limits of quantitation (LOQs) and applied to other feed samples. Good quantitation results were achieved for all AA, with coefficients of determination (R2) over 0.995; LODs at 0.2-28.2 and LOQs at 0.7-94.1 ng/mL; intraday and interday precision <14.9% relative standard deviation; blank recovery between 75.6 and 116.2%; and sample recovery between 75.6 and 118.0%. Overall, AA concentrations were similar to literature values, and there was a tendency for higher N recovery as AA. In conclusion, an efficient and robust method was validated to routinely analyze AA for appropriate characterization in diet formulation for dairy cattle.
摘要：
目前用于反刍动物营养中氨基酸（AA）分析的分析方法耗时且昂贵。本研究旨在开发一种更快的AA分析方法，更有效率,崎岖,和可访问的。选择了四个代表性基质进行方法开发和验证：牛奶，组织,饲料，和美国国家标准技术研究院的大豆粉标准参考材料。酸和碱水解用于分析18AA。使用Z-HILIC柱在18分钟的运行中与三重四极杆LC/MS系统在正和负电喷雾电离中进行AA的分离，以进行鉴定和定量。对该方法的回收率进行了评估，精度,校准曲线线性，以及检测限（LOD）和定量限（LOQ），并应用于其他饲料样品。所有AA均取得了良好的定量结果，测定系数（R2）超过0.995；LOD为0.2-28.2，LOQs为0.7-94.1ng/mL；日内和日间精密度<14.9％相对标准偏差；空白回收率在75.6和116.2％之间；样品回收率在75.6和118.0％之间。总的来说,AA浓度与文献值相似，并且有较高的N回收率作为AA的趋势。总之,验证了一种有效且可靠的方法，可以常规分析AA，以确定奶牛饮食配方中的适当特征。
