Sustainable Microextraction Using Switchable Solubility Solvent for the Liquid Chromatographic Determination of Three Profenoid Drugs in Urine Samples

Herein, a switchable solubility solvent (sodium salicylate) was employed for the microextraction of “profenoid” drugs (i.e., ketoprofen, fenoprofen, and flurbiprofen) from human urine samples. This approach utilizes the phase transition of salicylic acid (0.75 mol/L) by altering the sample's pH (addition of 10 µL of H₃PO₄ 10 M), facilitating efficient dispersion and phase separation in a single step. The solidified salicylic acid was easily collected using a syringe filter (nylon). In addition, the extensive contact area between the solidified solvent and the sample solution ensured effective extraction of the target analyte. The critical experimental parameters affecting the extraction performance of the analytes were examined. The separation of the drugs was carried out on a C₁₈ analytical column using gradient elution. Excellent linearity was observed in the dynamic range of 50–3000 ng/mL while the precision (%RSD) was less than 14.3% in all cases. The intraday and interday trueness were satisfactory, being in the range of 82.3%–110.1%. The green potential of the proposed analytical scheme was examined based on AGREEprep, ComplexMoGAPI, CACI, and AGREE metric tools. The developed method was utilized for the analysis of authentic urine samples after oral administration of a ketoprofen-containing formulation.