Solid phase extraction as a cleanup step before microextraction of diclofenac and mefenamic acid using nanostructured solvent

► Solid phase extraction followed by supramolecular solvent formation was introduced. ► SUPRAS generated from solutions of decanoic acid in THF by addition of H2O. ► Parameters affecting the SPE-SUPRASF process were investigated and optimized. ► The method was used for extraction of diclofenac and mefenamic acids from urine. ► Enrichment factors in the range of 431-489 were obtained for the drugs.