Ke Xing, Zhang Jingshun, Lai Shiyun, Chen Qi, Zhang Yu, Jiang Yirong, Mo Weimin, Ren Yiping
College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, China.
Zhejiang Provincial Center for Disease Control and Prevention, No. 630, Xincheng Road, Hangzhou, Zhejiang, 310051, China.
Anal Bioanal Chem. 2017 Jan;409(1):213-224. doi: 10.1007/s00216-016-9987-9. Epub 2016 Oct 19.
The aim of the study was to develop a method for quantification of cow's whey and whole milk powder in goat or sheep milk products including infant formula. A ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was established for simultaneous quantification of four caseins and two major whey proteins by detecting their signature peptides, which were able to act as markers for differentiating goat or sheep from cow whey and whole milk powder in infant formulas. The signature peptides were screened based on the computational prediction by Biolynx software, and confirmed by database searching after analysis of liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (LC-Q-TOF-MS). The isotopic-labeled signature peptide was used as internal standard to compensate the matrix effect. The limits of quantification were 0.01-0.05 g/100 g for target proteins. The observed recovery rates ranged from 82.3 to 116.6 % and the reproducibility was excellent (RSD <12 %) at different spiking levels. The RSDs of intra- and inter-day precision were 2.8-6.2 and 3.3-9.8 %, respectively. The multiple reaction monitoring method was successfully applied to milk powder with different composition, showing high specificity and accuracy in detection of species involved. The calculating formula was designed to assess the composition of adulteration in the actual detection of infant formulas. These results highlight applicability of this method for the detection of infant formulas with complicated matrix.
本研究的目的是开发一种方法，用于定量分析山羊或绵羊奶制品（包括婴儿配方奶粉）中的牛乳清和全脂奶粉。建立了一种超高效液相色谱-串联质谱（UHPLC-MS/MS）方法，通过检测四种酪蛋白和两种主要乳清蛋白的特征肽来同时定量分析它们，这些特征肽能够作为区分婴儿配方奶粉中山羊或绵羊乳清及全脂奶粉与牛乳清及全脂奶粉的标志物。基于Biolynx软件的计算预测筛选特征肽，并在液相色谱-四极杆-飞行时间串联质谱（LC-Q-TOF-MS）分析后通过数据库搜索进行确认。使用同位素标记的特征肽作为内标来补偿基质效应。目标蛋白的定量限为0.01 - 0.05 g/100 g。在不同加标水平下，观察到的回收率范围为82.3%至116.6%，重现性良好（RSD <12%）。日内和日间精密度的RSD分别为2.8 - 6.2%和3.3 - 9.8%。多反应监测方法成功应用于不同成分的奶粉，在检测相关物种时显示出高特异性和准确性。设计了计算公式以评估婴儿配方奶粉实际检测中的掺假成分。这些结果突出了该方法在检测基质复杂的婴儿配方奶粉方面的适用性。
