Analysis of flavonoids in citrus fruits by capillary zone electrophoresis coupled with quadrupole time-of-flight mass spectrometry using chemometrics.

• A CE–ESI-Q-TOF-MS method was developed for analysis of natural flavonoids. • HCA and PLS-DA were applied for citrus fruits differentiation. • The proposed method is rapid, efficient, economical. A rapid, efficient and simple method using capillary electrophoresis-electrospray ionization-quadrupole time-of-flight mass spectrometry (CE-ESI-Q-TOF-MS) was developed for the determination of the eight flavonoids (schaftoside, rutin, hesperidin, naringenin, naringin, violanthin, hesperitin and kaempferol) in 23 citrus samples. CE and ESI-Q-TOF conditions (e.g. nebulizer gas pressure, drying gas flow rate and temperature, sheath liquid composition, BGE composition and pH) were studied to obtain an optimal analytical identification and separation. The linear calibration was investigated ranged from 10 to 300 μg/mL for the six analytes, and had a good linearity with correlation coefficient of determination ranged from 0.9901 to 0.9995. The repeatability was tested by intra (n = 3) and the RSDs for migration time and peak area were within 0.43–2.30 % and 13.02–24.60 %, respectively. In addition, 23 investigated citrus samples were classified into 3 clusters according to different recognition program modes hierarchical cluster analysis and partial least squares discriminant analysis based on the peak areas of 8 target components. [ABSTRACT FROM AUTHOR]