Reversible switchable deep eutectic solvent for dispersive liquid–liquid microextraction of non-steroidal anti-inflammatory drugs in biological and wastewater samples combined with high-performance liquid chromatography

Abstract

The development of fast and simple bioanalytical methods for determining drugs is increasing. In the present study, a pH-induced reversible switchable deep eutectic solvent based on dispersive liquid–liquid microextraction was assessed (sDES-DLLME) for the analysis of three non-steroidal anti-inflammatory drugs (salicylic acid, mefenamic acid, and diclofenac) in plasma, urine and wastewater samples and their analysis by high-performance liquid chromatography. In this study, the switching process of DES (sDES) composed of 2-isopropyl-5-methylphenol (thymol) and a fatty acid was performed by pH adjustment. By adding NaOH to the sample solution, a homogeneous phase was achieved based on the hydrophilic form of sDES, and a two-phase system was obtained by adding an inorganic acid (HCl) to return the hydrophobicity. The important factors, such as DES type, the DES volume and the conditions of NaOH and HCl solutions were perused. Under optimal conditions, the limits of detection and limits of quantification were acquired in the range from 1 to 3 μg L−1 and 3 to 9.2 μg L−1 for three analytes, respectively. The ER% and EF values were to be in the range of 93.3 to 97.2 % and 112 to 117 for all analytes. A good linear range was declared up to 500 μg L−1 while the precision (%RSD) as the inter-day and intra-day in different samples was in the range of 4.6–6.1 % and 2.7–5.1 % respectively. Subsequently, the developed method was utilized to analyze the drugs in human urine, plasma and wastewater samples.