KCS

Polyphenols are phytochemicals that exist in grapes and are beneficial to human health. In this study, resveratrol, oxyresveratrol and piceatannol in wine were extracted by deep eutectic solvent based on dispersive liquid-liquid microextraction (DES-DLLME), and a method for quantification these polyphenols using high performance piquid chromatograph - UV/Vis (HPLC-UV/Vis) was established. Several parameters for sample extraction, clean-up and concentration were optimized and verified by Central Composite Design (CCD) using Design Expert 11. The optimized sample preparation parameters are as follows: type and ratio of DES as extraction solvent, methyltributylammonium chloride / decanoic acid(1:3 molar ratio); type and volume of basic solvent, KHCO₃ and 1.3 mL; volume of acetic, anhydride, 250 μL; time of derivatization, 5min; type of dispersive solvent, methanol; ratio of extraction and dispersive solvent, 1:5.5; and salt 1.0 g. Chromatographic separation with HPLC/UV-vis was performed using Agilent HPLC 1100 series, ACME C₁₈ (4.6mm id × 150 mm length, 5 μm particle size) column and gradient elution mode using water and 70% methanol. From the established extraction and HPLC-UV conditions, the limit of detection (LOD) and limit of quantitation (LOQ) of three analytes in the spiked sample were 6.09 - 11.77 μg/L and 18.47 - 35.66 μg/L, respectively. Recovery studies were performed at low, medium and high concentration range in calibration curve, and accuracy and precision in working range were 81.33 - 108.25 % and 2.03 - 10.73 RSD %, respectively. The calibration curves for the quantitative analysis were obtained the concentration range of 18.47 - 184.7 μg/L, 35.66 - 356.6 μg/L and 27.42 - 274.2 μg/L with correlation coefficient(r²) from 0.9909 to 0.9984, respectively. The proposed method was applied to the determination of polyphenols in wine samples.