Simultaneous Determination of Phenolics and Polymethoxylated Flavones in Citrus Fruits by Ultra-High Performance Liquid Chromatography Coupled with Triple-Quadrupole Mass Spectrometry (UHPLC-QqQ-MS)

Phenolic and polymethoxylated flavones are important bioactive components in citrus fruit. Here, a rapid and sensitive method based on ultra-high performance liquid chromatography coupled with triple-quadrupole mass spectrometry (UHPLC-QqQ-MS) was developed for the simultaneous determination of phenolic and polymethoxylated flavones in the peels and pulp of mandarins, tangelos, and oranges. Three phenolic acids and eight flavonoids, including polymethoxylated flavones, were separated and determined using positive and negative ion modes in a single chromatographic run of only 11 min using the multiple reaction monitoring detection mode. The method was validated with high recoveries from 96.1% to 103.5%, good precision with interday relative standard deviations less than or equal to 7.3%, intraday relative standard deviations <= 2.64%, low limits of detection from 1.0 to 18 mu g L-1, and low limits of quantitation in the range from 3.0 to 61 mu g L-1. The application of this UHPLC-QqQ-MS/MS method to the citrus extracts of three cultivars showed that mandarin fruits contained the highest total amounts of the 11 analytes, followed by tangelos and oranges. This study provides a reliable and quantitative method that can be used for the development of functional products and quality evaluation of citrus fruits.