Deep eutectic solvent-based emulsification liquid-liquid microextraction coupled with HPLC-UV for the analysis of phenoxy acid herbicides in paddy field water samples

An emulsification liquid-liquid microextraction (ELLME) method was successfully developed using phenolic based deep eutectic solvent (DES) as an extraction solvent for the determination of phenoxy acid herbicides, dicamba and MCPA in environmental water samples. Five different phenolics based DES were successfully synthesized by using phenol (DES 1), 2-chlorophenol (DES 2), 3-chlorophenol (DES 3), 4-chlorophenol (DES 4) and 3,4-dichlorophenol (DES 6) as the hydrogen-bond donor (HBD) and choline chloride as the hydrogen-bond acceptor (HBA). The DESs were mixed at a 1:2 ratio. A homogenous solution (clear solution) was observed upon the completion of the successful synthesis. The synthesized DESs were characterised by using FTIR and NMR. Under optimum ELLME conditions (50 µL of DES 2 as extraction solvent; 100 µL of THF as emulsifier solvent; pH 2; extraction time; 5 min), enrichment factor (EF) obtained for dicamba and MCPA were 43.1 and 59.7, respectively. Limit of detection (LOD) and l...