Advanced spectrofluorimetric determination of ascorbic acid via serotonin hydrochloride quenching using a twin solar cell device with eight-angled blue radiation sources

Abstract

A novel spectrofluorimetric flow injection analysis (FIA) method was developed for the selective quantification of ascorbic acid via fluorescence quenching of serotonin hydrochloride. The system employs a custom-designed photometric array comprising 16 irradiation sources arranged in a dual-axis matrix—eight aligned horizontally and eight orthogonally, enabling multi-angle excitation and enhanced spectral resolution. Fluorescence signals were captured using a twin-pair solar cell detector, offering high sensitivity and minimal optical interference. The method exhibited a linear calibration range of 0.1–30 μg/mL with a correlation coefficient (r²) of 0.9966, a limit of detection (LOD) of 0.025 μmol /L, equivalent to 4.403 * 10⁻⁴ μg/mL per sample (0.1 mL (and limit of quantitative (LOQ) of 99.381 * 10⁻³ $\mathrm{\mu g}/\mathrm{ml}$. Precision and accuracy were confirmed through intra- and inter-day validation, yielding relative standard deviations (RSD) below 2% and recovery rates exceeding 99%. Statistical comparison with conventional fluorometric techniques using a paired t-test revealed no significant difference at the 95% confidence level (p > 0.05), affirming the method's reliability. The proposed system supports high-throughput analysis of up to 50 samples per hour, with reduced reagent consumption and minimal environmental impact. Its robustness, cost-efficiency, and analytical performance render it a promising tool for routine pharmaceutical quality control and environmental monitoring.