Simultaneous analysis of benzoic and sorbic acids in orange juice using thymol/ water natural deep eutectic solvent and DLLME method followed by high performance liquid chromatography

In this study, the analytical and developed method was successfully validated for the simultaneous determination of benzoic acid (BA) and Sorbic acid (SA) by natural deep eutectic solvent (DES) composed of thymol/water and dispersive liquid–liquid microextraction (DLLME) followed by HPLC/UV in orange juice samples. A response surface methodology (RSM) based on a central composite design (CCD) was applied for optimization of the main variables. The significant parameters including DES volume (600 µL), dispersive solvent volume (THF) (709 µL), sample volume (11.1 mL), salt amount (5% w/v), and vortex time (10 min) were optimized. Under the optimal conditions, the limits of detection (LOD) and limits of quantifications (LOQ) were obtained 0.468 and 1.419 mg L⁻¹ for BA and 2.517 and 7.628 mg L⁻¹ for SA, respectively. The recovery values were between 94 and 97%. R² of BA and SA were 0.9940 and 0.9921, respectively.