Determination of Oleanolic acid and Ursolic acid in loquat leaf extract By Liquid Chromatography-Tandem Mass Spectrometry

Ursolic acid (UA) and oleanolic acid (OA) belong to a class of triterpenic acid, which play significant bioactive roles in anti-inflammatory, antitumor as well as enhancing the cellular immune system. However, due to the lack of suitable chromophoric or ionization groups in molecular structures, both UV and MS responses are far from satisfaction. In this study, a highly sensitive method based on derivatization and LC-MS/MS has been developed. After being extracted, a pair of stable isotope probes, 2-dimethylaminoethylamine (DMED) and d4-2-dimethylaminoethylamine (d4-DMED) were added for derivatization. The generated heavy labeled triterpenic acids were used as internal standards for quantification, the detection sensitivities of analytes improved sharply, the detection limits of OA and UA were 0.92 and 1.06 ng/L, respectively.