Sugaring-out assisted liquid-liquid extraction coupled with high performance liquid chromatography-electrochemical detection for the determination of 17 phenolic compounds in honey

In this work, a simple sugaring-out assisted liquid-liquid extraction (SULLE) method coupled with high performance liquid chromatography-electrochemical detection (HPLC-ECD) has been developed for rapid and sensitive determination of 17 phenolic compounds in honey. To achieve the maximum extraction efficiency of target analytes, several parameters, such as pH, ionic strength, extraction times and the volume of extracting solvent were optimized. Chromatographic separation was performed on a C18 column with a gradient methanol/aqueous formic acid elution, and the ECD was set at 1.0 V in oxidative mode. Under the optimal conditions, good linearity was obtained for 17 phenolic compounds with the coefficients of determination (R2) higher than 0.9986 in the range of 0.05-20 μg mL-1. The limits of detection (LODs, S/N = 3) for the 17 phenolic compounds were in the range of 0.20-1.26 μg kg-1 by ECD, 9-83 times lower than those obtained with UV detection. Satisfactory recoveries between 79.8% and 105.7% were obtained for spiked honey samples with relative standard deviations (RSD) less than 5.1%. Compared with conventional LLE method, the proposed SULLE method provided higher extraction efficiency and had advantages of rapidity, ease of operation, much less consumption of organic solvents and samples. The proposed HPLC-ECD method featuring excellent sensitivity and selectivity has been applied to the quantification of phenolic compounds in honey samples of different floral origin.