反相高效液相色谱法检测奶粉中含硫氨基酸

Determination of Sulfur-Containing Amino Acids in Milk Powder by Reverse-Phase High Performance Liquid Chromatography

目的:建立奶粉中含硫氨基酸反相高效液相色谱检测方法,为含硫氨基酸检测提供新思路。方法:用常规酸水解和氧化水解法水解奶粉,对水解条件和色谱分离和检测条件进行研究,用反相高效液相色谱法测定奶粉中的含硫氨基酸。结果:蛋氨酸(Met)、胱氨酸[(Cys)2]检出限分别为0.7、0.3μmol/L,定量检测范围均为10～300μmol/L,相关系数分别为0.9993、0.9992。经酸水解和氧化水解处理的奶粉,所测得的Met含量无显著差异,均为0.43g/100g,(Cys)2的含量则分别为0.06、0.14g/100g,差异显著。结论:奶粉中Met含量的高效液相色谱HPLC检测可选用酸水解或氧化水解中任一种前处理方法,(Cys)2含量的测定只能采用氧化法进行前处理。

Objective： To establish a new method for the determination of sulfur-containing amino acids in milk powder by reverse-phase high performance liquid chromatography（HPLC）.Methods： Milk powder was subjected to acid hydrolysis or oxidation and subsequent hydrolysis.The optimal hydrolysis conditions and chromatographic separation conditions were investigated.Results： The detection limits of the method for methionine and（Cys）2 were 0.7μmol/L and 0.3μmol/L,respectively,and the linear ranges were both 10-300μmol/L with correlation coefficients of 0.9993 and 0.9992,respectively.In addition,no significant difference was observed between the results of methionine content obtained with acid hydrolysis and oxidation and subsequent hydrolysis,which were both 0.43 g/100 g,whereas the（Cys）2 contents were 0.06 g/100 g and 0.15 g/100 g,respectively,showing a significant difference.Conclusion： Both acid hydrolysis and oxidation followed by hydrolysis can be used for the detection of methionine in milk powder,but only the latter is suitable for the detection of（Cys）2.