Rapid and Sensitive Determination of L-carnitine and Acetyl-L-carnitine in Liquid Milk Samples with Capillary Zone Electrophoresis Using Indirect UV Detection

The purpose of this study was to establish a new capillary zone electrophoresis method with indirect UV detection for determining the concentration of L-carnitine and acetyl-L-carnitine in liquid milk samples. Orthogonal experimental design was applied to arrange and optimize the experimental conditions. Under selected conditions (using melamine as the additive), both L-carnitine and acetyl-L-carnitine could be detected in 6 min, with satisfied reproducibilities (RSD% of migration times <0.8%), linearities (r ² > 0.995), recoveries (>90%), and relative low LODs (3.0 and 5.0 μmol/L for L-carnitine and acetyl-L-carnitine, respectively). The proposed method was successfully applied to the assay of nine brands of bovine milk samples and shows potential for analyzing L-carnitine and acetyl-L-carnitine in other biosamples.