Determination of polar purines in human serum via a cyclodextrin polymer-based solid-phase microextraction fiber

An efficient analytical scheme for detecting six purines in human serum samples was proposed by coupling a cyclodextrin polymer-based solid-phase microextraction (SPME) fiber with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The cyclodextrin polymer coating provides abundant porous adsorption sites and cyclodextrin-assisted host-guest recognition toward nitrogen-rich purine structures, enabling efficient enrichment of highly polar purines from complex serum matrices. Compared with commercial fibers, the prepared fiber exhibited enhanced extraction performance, yielding analyte peak-area responses that were 3–267 times higher under identical experimental conditions. The method showed good linearity over the range of 1–2000 μg l -1 , low limits of detection of 0.05–3.3 μg l -1 , and satisfactory apparent spiked recoveries of 77.0–112.0%. Acceptable reproducibility was obtained with relative standard deviations of 1.49–17.4% for single-fiber repeatability and 2.60–14.0% for fiber-to-fiber reproducibility. The use of SPME and a small desorption volume further reduces solvent consumption and sample-preparation waste, supporting the potential green analytical features of the proposed method. Application of the method to human serum samples was performed as a preliminary demonstration of the method feasibility for real biological sample analysis. Overall, the proposed method offers a sensitive, and practical analytical approach for purine metabolite determination in biological samples, with promising potential for future clinical and metabolic investigations after further studies with larger sample cohorts.