Salivette swab-based pipette-tip microextraction for the HPLC determination of urinary PDE5 inhibitors

A novel pipette tip microextraction (PT-μE) device based on the biocompatible Salivette® material was developed for the determination of three phosphodiesterase type 5 inhibitors (PDE5Is) – namely sildenafil, avanafil and vardenafil – in human urine samples. Although Salivette® swabs are commercially available for salivary cortisol collection, they were successfully repurposed as extraction sorbents within a pipette-tip configuration. The proposed PT-μE device offers a simple, rapid, and cost-effective analytical workflow requiring less than 7 min per analysis. Critical experimental parameters affecting extraction efficiency were systematically optimized, and analyte separation was achieved by HPLC-UV. Adsorption experiments were performed to estimate the adsorption capacity of the sorbent. The tip-to-tip reproducibility was less than 11%. The method was validated according to standard performance criteria, demonstrating satisfactory selectivity, linearity (100–2000 ng/mL), accuracy (88.6–114.3%), precision (< 11.9%), LODs (22–31 ng/mL), and robustness. Method greenness was evaluated using the unified green analytical procedure index (MA tool), confirming its environmentally benign character. The applicability of the method was verified through the successful quantification of sildenafil in authentic urine samples collected from a volunteer following oral administration of a commercial tablet. The developed approach represents an efficient, sustainable, and versatile tool for the rapid monitoring of PDE5Is in biological matrices.