Dispersive micro-solid phase extraction of uric acid from human serum using a CuFe₂O₄@Go-activated carbon hybrid...

A dispersive micro-solid phase extraction (D-µSPE) method was developed for the efficient extraction and spectrophotometric determination of uric acid in human serum using a CuFe₂O₄/graphene oxide/activated carbon (CuFe₂O₄/GO/AC) nanocomposite. The sorbent was synthesized via a green approach using green tea leaf extract and characterized by FTIR and SEM analyses, confirming the successful formation of a layered carbon structure decorated with finely dispersed metal oxide nanoparticles. Important experimental parameters affecting extraction efficiency, including sample pH, sorbent amount, extraction time, sample volume, desorption solvent type and volume, and the number of draw/eject cycles, were systematically optimized. Under the optimized conditions, the proposed method exhibited a wide linear dynamic range of 5-450 µM with a correlation coefficient (R²) of 0.996. The limit of detection and limit of quantification were estimated to be 1.14 µM and 3.44 µM, respectively. The method showed good precision, with intra- and inter-day relative standard deviations below 5%. Satisfactory recoveries (96.0-104.0%) were obtained for spiked human serum samples, indicating negligible matrix effects. In addition, the sorbent exhibited good reusability, retaining over 90% of its initial extraction efficiency after seven consecutive extraction-desorption cycles. The proposed D-µSPE method offers a simple, low-cost, and environmentally friendly alternative for the determination of uric acid in biological samples and shows strong potential for routine clinical and analytical applications.