Development of an Integrated UPLC-QTOF-MS/MS and HPLC-QqQ-MS/MS Method for Polyphenol Analysis in Sea Buckthorn Juice

An integrated analytical method combining ultra-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF-MS/MS) for qualitative screening and high-performance liquid chromatography coupled to triple-quadrupole tandem mass spectrometry (HPLC-QqQ-MS/MS) for targeted quantification was developed for the comprehensive analysis of polyphenols in sea buckthorn juice. UPLC-QTOF-MS/MS screening yielded 42 candidate polyphenol annotations, from which 15 representative compounds spanning phenolic acids, flavan-3-ols, and flavonols were selected for targeted quantification. The optimized HPLC-QqQ-MS/MS conditions used acetonitrile–0.1% aqueous formic acid as the mobile-phase system, extraction with 70% ethanol followed by treatment with 0.01 mol/L HCl, and a sample-to-solvent ratio of 1:15 (g/mL). The quantitative method showed coefficients of determination (R2) > 0.99, LODs of 0.0010–0.0054 μg/g, LOQs of 0.0033–0.0179 μg/g, and recoveries of 76.8–105.7% with RSDs ≤ 4.4%. The established method was applied to seven sea buckthorn juice samples, with the summed concentrations of the 15 target polyphenols ranging from 34.25 to 94.86 μg/g. Sample No. 7 (Daguo Shaji No. 7) showed the highest summed concentration of the 15 target polyphenols, while rutin was the most abundant quantified compound in all seven samples. The developed method links high-resolution mass spectrometric screening with validated targeted quantification, enabling the selection of target polyphenols based on the chemical composition of actual samples and providing a reliable analytical approach for polyphenol profiling and quantification in sea buckthorn juice.