Microextraction and gas chromatography–flame ionization determination of five antiepileptic drugs in biological samples using amino acid-based deep eutectic ionic liquids

Abstract

This study investigated the use of amino acid-based deep eutectic solvents (AADESs) in the ultrasound assisted reverse-phase emulsification microextraction (UARPEME) of five antiepileptic drugs (AEDs) from biological samples. The extraction was performed by dispersing the AADES into the sample solution using ultrasonic irradiation. After completing extraction, the sample solution was centrifuged. Then, the pre-concentrated AEDs in the AADES (upper phase) were derivatized by adding phenyltrimethylammonium hydroxide solution to it. The derivatized analytes were then eluted with n-hexane and it was injected directly into the gas chromatography–flame ionization detection (GC–FID) system to determine target analytes after the methylation reaction inside the injection chamber. The effective parameters of the proposed AADES–UARPEME method that comprises three consecutive extraction, derivatization and elution steps, were optimized using one Taguchi orthogonal array design and two central composite designs and evaluated by analysis of variance. The optimized method was successfully implemented to analyze AEDs in the human biological samples (serum, urine, breast-milk and hair) and acceptable results were obtained. The resultant calibration curves were linear over the concentration range of 0.5–850 μg/L (R2 > 0.998). The estimated limits of detection and quantification were lower than 0.5 μg/L and the improvement factors were between 1378 and 1409. The intra- and inter-day repeatability values varied below 5.3% (n = 5) and the relative recovery values were calculated between 90 and 110% for all samples.