建立了超高效合相色谱法（UPC²）拆分和测定婴幼儿配方乳粉中两种肉碱对映体（D-肉碱和L-肉碱）的方法。样品经0.1 mol·L^-1盐酸溶液超声提取5 min后，用1 mol·L^-1氢氧化钾溶液在60 ℃水浴中皂化30 min，离心，上清液在活化好的Oasis MCX型混合型强阳离子交换固相萃取柱上用含4%（体积分数）氨水的甲醇溶液洗脱。洗脱液经氮吹至近干，用含L-丙氨酸-β-萘胺的乙腈溶液在催化剂的作用下于20 ℃静置衍生60 min，离心、浓缩、过滤后，滤液中的目标物在Acquity Trefoil CEL1手性色谱柱上以不同体积比的超临界二氧化碳和含1%（体积分数）氨水的甲醇溶液组成的混合溶液为流动相进行梯度洗脱。结果表明，方法可以有效拆分肉碱外消旋体，两种肉碱对映体均在0.25~10.00 mg·L^-1内与其对应的峰面积呈线性关系，测定下限（10S/N）均为25 mg·kg^-1；对空白样品进行3个浓度水平的加标回收试验，回收率为93.0%~110%，测定值的相对标准偏差（n=6）为3.9%~5.5%；方法用于20个实际样品的分析，未检出D-肉碱，而L-肉碱测定值满足GB 28050-2011和GB 13432-2013的要求，且方法与GB 29989-2013中的分光光度法无显著性差异。

A method for chiral separation and determination of 2 carnitine enantiomers (D-carnitine and L-carnitine) in infant formula by ultra-performance convergence chromatography (UPC²) was established. Samples were extracted by ultrasound with 0.1 mol·L^-1 hydrochloric acid solution for 5 min, and saponified with 1 mol·L^-1 potassium hydroxide solution in a water bath at 60℃ for 30 min. The supernatant obtained by centrifugation was purified on an activated Oasis MCX type mixed strong cation exchange solid phase extraction column, and eluted with methanol solution containing 4% (φ) ammonium hydroxide. The eluate was blown to near dryness with nitrogen and derivatized with acetonitrile solution containing L-alanine-β-naphthylamine in the presence of catalyst at 20℃ for 60 min. After centrifugation, concentration and filtration, the targets in the filtrate were subjected to gradient elution on an Acquity Trefoil CEL1 chiral column with mobile phases composed of supercritical carbon dioxide and methanol solution containing 1% (φ) ammonium hydroxide ammonium hydroxide at different volume ratios. The results showed that the method could effectively separate carnitine racemates, and linear relationships between mass concentrations of two carnitine enantiomers and their corresponding peak areas were kept in the range of 0.25-10.00 mg·L^-1, with the same lower limit of determination (10S/N) of 25 mg·kg^-1. Test for spiked recovery was made on the blank samples at 3 concentration levels, giving results of recovery in the range of 93.0%-110%, with RSDs (n=6) of the determined values in the range of 3.9%-5.5%. The proposed method was used for the analysis of 20 actual samples, and no D-carnitine was detected, while the determined values of L-carnitine met the requirements of GB 28050-2011 and GB 13432-2013, and there was no significant difference between the prescribed method and the spectrophotometric method of GB 29989-2013.