Emulsification liquid-liquid micro-extraction based on natural deep eutectic solvent for (triarylmethane) dyes determination

A green and straightforward emulsification liquid-liquid micro-extraction combined with the HPLC approach was established for the determination of malachite green (MG) and crystal violet (CV) in shrimp water samples using deep eutectic solvent (DES). The DES was made up of thymol and camphor at a molar ratio of 1:1, which was used as extraction agent, and nonionic surfactant TMN-10 (branched secondary alcohol ethoxylate) was used as an emulsifying agent. A series of parameters were optimized including pH, volume of DES and emulsifying agent, salt concentration as well as centrifugal time. Under optimal conditions, the calibration graphs were linear in the concentration range from 0.2 to 200 mu g L-1 for MG and CV. MG and CV of the relative standard deviations (% RSDs) were 1.4 and 2.3, and the limits of detections were 0.09 and 0.13 mu g L-1, respectively. Also, the proposed method was applied to analyze the MG and CV in shrimp water samples, and the observed recoveries were between 82.0-99.3% and 78.0-91.4%, respectively.