Spectrophotometric determination of lamotrigine in plasma samples: Ultrasound-assisted emulsification-microextraction based on a hydrophobic deep eutectic solvent followed by back-extraction

[Display omitted] •A hydrophobic deep eutectic solvent (DES) was prepared based on 1-phenylethanol.•Ultrasound-assisted emulsification-microextraction based on DES was developed.•Back-extraction used to retrieve lamotrigine from the DES phase to aqueous phase.•A spectrophotometric method for determination of lamotrigine in plasma samples.•Wide linear range, low limit of detection, and good precision and accuracy obtained. In this study, sensitive detection of lamotrigine in human plasma samples was realized at a low cost approach through ultrasound-assisted emulsification-microextraction based on using a hydrophobic deep eutectic solvent followed by back-extraction (USAEME-DES-BE) method. After extraction, detection and quantification of lamotrigine were done by spectrophotometry in the UV region. The hydrophobicity of the deep eutectic solvent not only eliminates the need of the third solvent as an emulsifying agent but also helps to retrieve lamotrigine from the DES by back-extraction to another aqueous phase. The back extraction process allowed the drug to be measured in the UV region. Central composite design in combination with a desirability function approach was applied for the optimization of the USAEME-DES-BE procedure. Essential factors in the method efficiency were discussed, such as back-extraction solution, time of back-extraction, the ratio of DES components, pH, the volume of DES, salt concentration, and sonication time. The method exhibited a wide dynamic linear range from 0.5 to 10 µg mL−1 and a limit of detection of 0.15 μg mL−1. The established method was successfully applied to determine lamotrigine in human plasma samples with satisfactory relative recoveries.