Solvent-Assisted dispersive solid phase extraction of diclofenac from human serum and pharmaceutical tablets quantified by high-performance liquid chromatography

•We developed a novel procedure based on solvent assisted dispersive solid phase extraction to determine trace diclofenac in tablets and human serum samples.•Ease of operation, rapidity, cost-effectiveness, low organic solvent consumption, high recovery can be mentioned as the advantages of the developed method.•The proposed preconcentration method allows diclofenac determination in real samples at µg L−1 levels. This study developed a novel solvent-assisted dispersive solid phase extraction (SADSPE) process in combination with HPLC for the determination of diclofenac (DIC) in tablets and human serum. This route required a few milligrams of benzophenone sorbent dispersed in the specimen solution using a disperser solvent giving rise to the formation of a cloudy solution which was then centrifuged. Ethanol was utilized for dissolving the analyte-enriched sorbent. The extract was then analyzed through the use of high-performance liquid chromatography (HPLC) equipped with UV-detection to quantify the DIC. Different parameters of the procedure including solution pH, sorbent type and content, disperser solvent type and volume, extraction time, and ionic strength were closely analyzed and optimized. The results of optimization were as follows: pH=2.5; 20 mg of benzophenone as sorbent, 1 mL of ethanol as disperser solvent, extraction time=30 s; and 0.5 mol L−1 of sodium chloride. The extracted analyte was dissolved by using 0.5 mL of ethanol. Optimized conditions led to the preconcentration factor of 40 and the limit of detection (LOD) of 0.47 µg L−1. The proposed method could be successfully employed for diclofenac determination in tablets and human serum samples (real and spiked samples), with recovery range of 96.7–97.9%.