A Green HPLC-PDA for Simultaneous Analysis of Coreopsin and Luteolin in Cosmos sulphureus: A Cost-Effective QC for Anti-Gout Phytomedicines

Coreopsin and luteolin possess strong antioxidant properties, particularly hypouricemic activities that may benefit gout treatment. We thereby develop and validate a first eco-friendly yet robust high-performance liquid chromatography with photodiode array detector method to simultaneously quantify these two markers of Cosmos sulphureus in both raw flowers and their 70% ethanol extracts. A gradient of acetonitrile–methanol–0.1% formic acid on a C18 column delivered baseline separation within 50 min. Single-step ultrasound extraction yielded 12 mg/g of coreopsin and enriched luteolin 2.5-fold compared with the dried flowers, making it suitable for routine quality control and further pharmacological research. Validation parameters, including system suitability, specificity, linearity, accuracy, precision, and robustness, were within the acceptable limits according to current international standards. Limits of detection/quantitation for coreopsin and luteolin were 0.20/0.66 and 0.25/0.82 µg/mL, respectively, and inter‑day precision stayed below 1.45% RSD. This procedure scored 82 on the Analytical Eco‑Scale, earning an excellent green analysis classification and a low operating cost. These findings provide a practical analytical foundation for the standardization, routine quality control, and future development of C. sulphureus–based anti-gout herbal products.