Dispersive liquid-liquid microextraction for the determination of flavonoid aglycone compounds in honey using liquid chromatography with diode array detection and time-of-flight mass spectrometry

A rapid approach for the determination of eight flavonoid aglycone compounds, baicalein, hesperitin, fisetin, naringenin, chrysin, myricetin, quercetin and kaempferol, in honey samples and related products has been optimized and validated. The enriched extracts obtained by dispersive liquid-liquid microextraction (DLLME) were analyzed by liquid chromatography with diode array detection coupled to electrospray ionization and time-of-flight mass spectrometry (LC-DAD-ESI-ToFMS). For DLLME, using acetonitrile and chloroform as disperser and extractant solvents, respectively, a Taguchi experimental method was applied to find the optimal combination of following six factors: disperser and extractant solvent volumes, sodium chloride concentration, pH of the aqueous phase, honey mass and centrifugation time. The sedimented organic phase obtained after centrifugation was evaporated, reconstituted in acetonitrile and submitted to LC. The matrix effect was evaluated, and it was concluded that sample quantification can be carried out against aqueous external standards when using DAD and by matrix-matched calibration in the case of ToFMS. Detection limits in the ranges of 0.4-4 and 0.01-0.5 ng g-1 were obtained for DAD and ToFMS, respectively. Satisfactory recovery values between 80 and 111% were obtained for three spiked samples. Honeys and related products were analyzed and flavonoids were found within a wide range. © 2014 Elsevier B.V. All rights reserved.