微波水解—氨基酸自动分析仪法测定饲料中色氨酸的含量

目的] 建立微波水解—氨基酸自动分析仪快速测定饲料中色氨酸含量的方法。方法] 以奶牛全混合日粮饲料（TMR）为研究对象,通过单因素试验和正交试验筛选微波碱水解最佳条件,联合氨基酸自动分析仪LCAK06/Na（4.6 mm×150 mm）色谱柱分离及快速测定饲料中色氨酸含量。结果] 水解温度是影响饲料色氨酸含量的最主要因素。微波碱水解测定饲料中色氨酸含量的最佳条件是：水解温度170 ℃、水解时间30 min、碱浓度5 mol/L,通过氨基酸自动分析仪测定TMR饲料色氨酸含量为0.14%。色氨酸在0.025~0.600 μmol/mL峰面积与浓度线性关系良好,相关系数（r）为0.999 7。定量限（LOQ）为0.05%,色氨酸回收率93%~104%,精密度RSD为3.58%。结论] 该方法高效、准确,检测结果与国家标准《饲料中色氨酸的测定》（GB/T 15400—2018）中的常规碱水解法对比无显著差异,对于饲料中色氨酸含量测定具有参考价值。

Determination of Tryptophan in Feed by Microwave Hydrolysis and Amino Acid Automatic Analyzer

Objective]To develop a rapid determination method for tryptophan in feed by microwave hydrolysis and amino acid automatic analyzer.Method]The optimum conditions of microwave alkaline hydrolysis were screened by single factor test and orthogonal test,and the tryptophan content in total mixed ration(TMR)of dairy cow was determined by the LCAK06/Na(4.6 mm×150 mm)column of automatic amino acid analyzer.Result]Hydrolysis temperature was the most important factor affecting tryptophan content in feed.The optimum conditions for determination of tryptophan in feed by microwave alkaline hydrolysis were as follows:hydrolysis temperature 170℃,hydrolysis time 30 min,alkali concentration 5 mol/L.The tryptophan content in TMR was 0.14%determined by amino acid automatic analyzer.The linear range of tryptophan was 0.025-0.60μmol/mL,and the correlation coefficient(r)was 0.9997.The limit of quantification(LOQ)was 0.05%,the recovery rate of tryptophan was 93%-104%,and the RSD of precision was 3.58%.Conclusion]The developed method is efficient and accurate,and there is no significant difference in detection results between this method and the conventional hydrolysis method in the national recommended standard of′Determination of Tryptophan in Feed′(GB/T 15400-2018),which has reference value for determination of tryptophan in feed.