高效液相色谱-串联质谱法测定婴幼儿配方奶粉中酪蛋白磷酸肽含量

Determination of Casein Phosphopeptides in Infant Formula by HPLC-MS/MS

建立一种同位素稀释-高效液相色谱-串联质谱法定量检测婴幼儿配方奶粉中酪蛋白磷酸肽(casein phosphopeptides,CPPs)含量的方法。经Q Exactive Orbitrap扫描,Uniprot蛋白质数据库初步确定CPPs所含肽段,根据质谱响应以及加标回收率等方法学验证实验进一步筛选确定CPPs的特征肽段。样品经过前处理后,采用ACQUITY UPLC BEH 300 C18色谱柱分离,多反应离子监测模式定量测定其中的CPPs特征肽。根据CPPs原料与CPPs特征肽含量的折算系数,从而确定出样品中CPPs的含量。方法学验证结果表明,所建立的方法在10~150 mg/100 g范围内线性关系良好,相关系数大于0.999。在高、中、低3水平加标实验中,回收率在96.2%~100.2%之间,日间重复性在5.3%~7.8%之间。方法定量限为1 mg/100 g,可以满足婴幼儿配方奶粉中不同CPPs含量水平的定量要求。

A new and sensitive method was developed for the determination of casein phosphopeptides(CPPs)in infant formulas by isotope dilution ultra-high performance liquid chromatography-triple-quadrupole tandem mass spectrometry(UPLC-TQ-MS/MS)under the multiple reaction monitoring(MRM)mode.The sample pretreatment procedure involved the addition of isotope-labeled signature peptide as an internal standard,followed by acid precipitation to remove casein from the sample.The signature peptide was chosen and identified from CPPs with Q Exactive Orbitrap based on Proteome Discoverer protein software searching.CPPs were separated on an ACQUITY UPLC BEH 300 C18 column.The content of CPPs in infant formulas was calculated based on the content of the signature peptide in CPPs and in sample.The results of method validation showed that a good linearity with R2>0.999 was achieved within the range from 10 to 150 mg/100 g.Satisfactory recovery(96.2%–100.2%)and inter-day reproducibility(5.3%–7.8%)were obtained at three spiked levels in blank infant formula matrices.The limit of quantification(LOQ)of the reported method was 1 mg/100 g for infant formula.This method can be suitable for the determination of the content of CPPs in infant formula.