本研究建立了固相萃取-同位素稀释-气相色谱-质谱法同时测定婴幼儿米粉中的5种甾醇的方法。样品经SPE小柱分离萃取后，无需皂化和衍生，通过加入氘代同位素内标，经固相萃取净化之后，再以HP-5 MS（30 m×0.25 mm×0.25 μm）色谱柱分离，通过采用选择离子监测（SIM）模式检测，以内标法定量，从而实现对甾醇的精确定性和准确定量。试验结果表明，5种甾醇在各自的限行范围内线性关系良好，相关系数均为大于0.9995，方法检出限（S/N=3）均为50 μg/kg，方法回收率在91.9%~107%之间，相对标准偏差（RSD，n=6）在3.1~4.6%之间，表明方法准确灵敏、回收率和精密度良好。该检测方法前处理简单，灵敏度高，重现性和准确性好，具有科学性及可操作性；适用于婴幼儿配方米粉中甾醇的检测。

A method for simultaneous determination of 5 sterols in infant formula rice flour by solid phase extraction-isotope dilution- gas chromatography-mass spectrometry was established in this study. Samples were separated and extracted on a SPE column without saponification and derivatization and purified by adding deuterium isotope internal standard withsolid phase extraction. Then target sterols were separated on a HP-5MS (30 m×0.25 mm×0.25 m) column, detected by a selected ion monitoring (SIM) mode and quantified by internal standard method, which could achieve the accurate characterization and quantification of sterols. The results showed that the fivesterols had good linearity in their respective linear ranges with the correlation coefficients greater than 0.9995, and the detectionlimits (S/N = 3) were all 50 g/kg for. In addition, the recoveries were 91.9%~107% and the relative standard deviations (RSDs, n = 6) were in the range of 3.1~4.6%. The proposed method had the advantages of simple pretreatment, high sensitivity, good reproducibility and accuracy, as well as scientificity and operability, which was suitable for the simultaneous determination of 5 sterols in infant formula rice flour.