Analysis of six preservatives in beverages using hydrophilic deep eutectic solvent as disperser in dispersive liquid-liquid microextraction based on the solidification of floating organic droplet

Abstract

In this work, a deep eutectic solvent (DES) composed of tetrabutylammonium bromide (TBABr) and acetic acid in a 1:2 M ratio was applied as the dispersive solvent for the dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO), using 1-decanol as extractant. Six preservatives (benzoic acid, BA; sorbic acid, SA; methyl paraben, MP; ethyl paraben, EP; propyl paraben PP; and butyl paraben, BP) in beverages were determined simultaneously through high-performance liquid chromatography with a diode array detector (HPLC-DAD). Under the optimal experimental condition that consists of 200 μL of disperser (TBABr: acetic acid, 1:2), 80 μL of extractant (1-decanol), 3 min of vortex time, 4.5 of pH, 2.5 g of NaCl, the proposed method showed satisfactory linearity in the range of 0.05-50.0 mg L^-1, with a correlation coefficient (R²) higher than 0.9998. The limits of detection (LODs) varied from 0.02 to 0.05 mg L^-1 and the limits of quantification (LOQs) varied from 0.05-0.1 mg L^-1. The relative standard deviations (intra-day and inter-days) were below 5 %. The developed method was successfully applied to the determination of preservatives in beverages.

Keywords: Beverages; DLLME-SFO; Deep eutectic solvents; Preservatives.