Multivariate Optimization of an Ultrasound-Assisted Deep Eutectic Solvent-Based Liquid-Phase Microextraction Method for HPLC-UV Analysis of Carbamazepine in Plasma

An ultrasound-assisted deep eutectic solvent-based liquid-phase microextraction (UA-DES-LPME) was established, for the first time, for the extraction of carbamazepine (CBZ) from human plasma samples. The extract was determined by HPLC-ultraviolet detection (HPLC-UV). A deep eutectic solvent (DES) was readily synthesized by mixing choline chloride and phenol (ChCl:Ph) in the mole ratio of 1:2 in ambient temperature and used without any further purification. In the present method, THF was used as an emulsifier agent. Some parameters, including the DES components mole ratio, kind of emulsifier agent, and salt addition effect, were optimized by a one-at-a-time approach. Central composite design (CCD) was used to optimize the rest of the effective parameters, including DES volume, pH, ultrasonication time, and THF volume. The optimum conditions were found to be: 11.78 pH, 314 mu L DES volume, 523 mu L THF volume, and 9.0 min ultrasonication time. The performance of the method was evaluated under optimum conditions, and the method exhibited good linearity over a concentration range of 10-1500 ng mL(-1), low limit of detection and quantitation, good precision, and high extraction recovery. Finally, the applicability of the method was assessed by analysis of the spiked plasma samples, and the results have shown high relative recoveries with good precision.