Vortex-assisted liquid-liquid microextraction based on hydrophobic deep eutectic solvent for determination of malondialdehyde and formaldehyde by HPLC-UV approach

A simple, and cost-effective vortex-assisted liquid-liquid microextraction (VALLME) based on hydrophobic deep eutectic solvent (DES) has been developed to extract malondialdehyde (MDA) and formaldehyde (FA) after derivatization with 2,4-dinitrophenylhydrazine (DNPH). Following the extraction process, a high performance liquid chromatography equipped with UV-Vis detector (HPLC-UV) was used for separation and quantification of the target analytes. The key variables affecting the derivatization process (concentration of DNPH, derivatization time, and derivatization temperature) were optimized by a central composite design (CCD). The effective parameters of VALLME including pH of the extraction medium, ionic strength, extracting agent (DES) volume, dispersive solvent volume, centrifugation rate, centrifugation time, and time of vortex were studied by a fractional factorial design to identify the significant factors effective in the extraction process. In the next step, a CCD was used to obtain the optimum conditions of the effective parameters. Under optimal conditions, good line-arities (R-2 > 0.99) in the concentration ranges of 5-3000 and 20-2000 ng mL(-1) were obtained for MDA and FA, respectively. The detection limits of MDA and FA were found as 2.0 and 10.0 ng mL(-1), respectively. The method was successfully applied to the quantification of both analytes in three different real samples (human urine, apple juice and rain water) and satisfactory results in terms of recoveries (91-112%) were achieved.