Method for detecting fat-soluble vitamins in infant milk powder

The invention provides a method for detecting fat-soluble vitamins in infant milk powder, which adopts liquid chromatography-mass spectrometry to simultaneously detect the content of vitamins in infant milk powder, and comprises the following steps: (1) pretreating a milk powder sample to be detected; (2) preparing a standard working solution for establishing a standard curve; (3) detecting the milk powder sample to be detected by adopting a liquid chromatography tandem mass spectrometer; wherein the fat-soluble vitamins comprise vitamin A, vitamin D3, vitamin E and vitamin K1; the liquid chromatography conditions are as follows: a gradient elution mode is adopted, a mobile phase A is a 0.1 +/-0.05% formic acid solution, and a mobile phase B is a methanol solution of 1 +/-0.1% dichloromethane. According to the method, the content of multiple fat-soluble vitamins in the milk powder can be rapidly detected at the same time, the method has high accuracy and precision, the sample treatment step can be simplified,