Determination of nine bioactive phenolic components usually found in apple juice by simultaneous UPLC-MS/MS

The functional food ingredients of apple juice can significantly change during processing, transportation, and storage, thus affecting the quality of the product. A simple and derivation-free analytical method based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and optimized for the simultaneous determination of functional food ingredients in apple juice bought in the market. Cleanup steps and chromatographic conditions were optimized to remove interference and decrease the matrix effect. The nine target analytes were separated on an Acquity UPLC system equipped with a BEH C18 column and detected by electrospray ionization source (ESI) operating in positive subsection acquisition mode under multiple reaction monitoring (MRM) conditions. The results showed that p-hydroxybenzoic acid, protocatechuate, caffeic acid, chlorogenic acid, epicatechin, phloridzin, hyperoside, procyanidin B₂, and rutin could be sufficiently separated for content determination within 6 min. In the concentration range of 20 μg/L-50 mg/L, nine standard samples exhibited a good linear fit with correlation coefficients above .985.