Microextraction of carbamazepine for its determination in biological samples by gas chromatography

Abstract

Introduction: Therapeutic drug monitooring is required for carbamazepine due to its complex pharmacokinetic properties. There are also other reasons such as lack of simple relationship between dose and plasma concentration of it and thus lack of simple relationship between prescribed dose and clinical response and also reporting of different therapeutic concentrations for the drug( between 4 and 12 μg/ml). Aim: A simple, fast, efficient, and environmentally friendly microextraction technique named salt induced liquid-liquid extraction combined with deep eutectic solvent based dispersive liquid-liquid microextraction method followed by gas chromatography-flame ionization detector was applied for the determination of urine samples. Method: In this method, sodium chloride (30% w/v) was dissolved in the sample solution (adjusted at pH=10) as phase separation agent and iso–propanol was added to the solution. After manually shaking, the solution was centrifuged and the supernatant phase was removed and mixed with choline chloride (ChCl): benzyl ethylenediamine (85 μL) and the mixture was rapidly dispersed into a deionized water containing 5.0 % w/v, sodium chloride and adjusted at pH=10. The cloudy solution was centrifuged and the sedimented phase was collected and one μL of it was injected into the determination system. The named DES was synthesised in lab by heating- vortex cycle method. Results: Under optimal conditions, the limits of detection and quantification 6.9 and 23.3 were obtained, respectively (ng/mL). The relative standard deviations for intra- and inter day assays were lower than 10%. Conclusion: In this study, an extraction method with high extraction recovery, efficiency, precision and sensitivty for the measurement of carbamazepine in biological samples is presented. In this method environmental damage is minimized by using DES in extraction procedure.