Determination of unconjugated non-steroidal anti-inflammatory drugs in biological fluids using air-assisted liquid–liquid microextraction combined with back extraction followed by high performance liquid chromatography

Abstract

An analytical method based on air-assisted liquid–liquid microextraction and high performance liquid chromatography-variable wavelength detector is presented for the extraction and determination of naproxen, diclofenac, and ibuprofen in biological fluids. In this technique, the target drugs are extracted into several microliters of chloroform from an aqueous sample (human plasma or urine) by using a syringe to repeatedly aspirate and disperse the aqueous solution and chloroform mixture. The enriched analytes are then back-extracted into an alkaline aqueous phase prior to their injection into the separation system. Various parameters affecting the extraction efficiency such as type and volume of extraction solvent, extraction times, salt addition, and pH were evaluated. Under optimum extraction conditions, this method showed low limits of detection and quantification between 0.20–0.52 and 0.58–1.60 ng mL⁻¹, respectively. Enrichment factors and extraction recoveries were in the ranges of 390–470 and 78–94%, respectively. The method was successfully applied to determine the unconjugated selected drugs in biological samples.