Validated Micelle-enhanced Spectrofluorimetric Determination of Serotonin in Human Urine

A micelle-enhanced spectrofluorimetric method was developed and validated for the determination of serotonin (5-hydroxytryptamine, 5-HT) in aqueous solutions and human urine. Fluorescence responses of 5-HT were evaluated in various surfactant systems, with Brij 700 and sodium dodecyl sulfate (SDS) providing significant signal enhancement. Under optimized conditions (λex 275 nm; λem 340 nm), the method exhibited linearity over 0.1–300 ng mL⁻¹ (R² ≥ 0.996), with limits of detection of 1.7 ng mL⁻¹ in Brij 700 and 2.4 ng mL⁻¹ in SDS. Validation according to ICH Q2(R1) guidelines confirmed good precision (intra-day RSD 1.3–3.6 %, inter-day RSD 3.7–4.3 %), accuracy, selectivity, and reproducibility. Recoveries from fortified urine samples ranged from 89–101 %, demonstrating minimal matrix effects. Compared to conventional chromatographic techniques (HPLC/GC), this micelle-enhanced method is faster, simpler, and cost-effective, making it particularly suitable for routine clinical monitoring of serotonin in human urine.