Development and Validation of Micelle-Enhanced Spectrofluorimetric Method for Determination of Serotonin in Human Urine

Abstract

Micelle-enhanced spectrofluorimetry has been successfully applied to detect various pharmaceutical and biological compounds. The present study describes the development and validation of a micelle-enhanced spectrofluorimetric method for the direct determination of serotonin in aqueous solutions and human urine. A micelle-enhanced spectrofluorimetric method was developed and validated for the direct determination of serotonin (5-hydroxytryptamine, 5-HT) in aqueous solutions and human urine. The effects of micellar media, pH, and surfactant concentration on fluorescence intensity were systematically investigated. Brij 700 (nonionic) and SDS (anionic) micelles significantly increased the fluorescence signal by providing a hydrophobic microenvironment that reduces solvent quenching and stabilises the excited state of 5-HT. The method exhibited excellent linearity over the 0.1–300 ng mL⁻¹ range, with low limits of detection (1.7–4.1 ng mL⁻¹) and quantification (3.3–13.5 ng mL⁻¹), high precision (RSD < 1.5 %), and reliable recoveries (89–101 %). The analytical performance was unaffected by endogenous urinary components, confirming good selectivity and robustness. Application to human urine samples using liquid–liquid or solid-phase extraction demonstrated accurate and reproducible quantification without the need for chromatographic separation. This approach provides a rapid, sensitive, and cost-effective alternative to conventional methods such as HPLC, highlighting the potential of micelle-enhanced spectrofluorimetry for clinical and bioanalytical monitoring of serotonin in complex biological matrices.