An easy, fast and efficient combination of ultrasonic assisted extraction (UAE) with liquid chromatography-mass spectrometry (LC-MS) was developed for the identification and quantification of ursolic acid (UA) and betulinic acid (BA) in apple peel extract of five clones of Gala and Fuji cultivars (Baigent, Fuji Mishima, Fuji Suprema, Fuji Select and Maxi Gala) from southern Brazil. UA and BA extraction using acetone as solvent was successfully performed. Chromatographic parameters of the analytical method include: positive electrospray ionization (ESI+) with a flow of 1 mL-1 in isocratic mode consisting of 80 % acetonitrile and 20 % ammonium acetate 10 mM pH 6.0, at room temperature. The method proved to be selective, sensitive, with LOD and LOQ of, 0.087 and 0.266 µg.mL-1 for BA, and 0.398 and 2.117 µg.mL-1 for UA, linear (r >0.99), precise, accurate and robust, for all analytes. The optimization of UAE combined with the LC-MS technique allowed completing the procedure (extraction and analysis) in less than 4 h. These methods were applied for first time characterization of five clones. The results demonstrated that the UAE-LC-MS method is applicable to routine analysis of triterpene acids in apple peel.
Key words: Triterpene, LC-MS, ultrasound, apple peel, ursolic acid, betulinic acid
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