Response Surface Methodology–Based Optimization of HPLC Conditions for Quantification of Paracetamol in Indonesian Traditional Medicines (Jamu)

Indonesian traditional herbal medicines (Jamu) are prohibited from containing active pharmaceutical ingredients (APIs). Nevertheless, reports indicate that some hyperuricemia jamu products still contain such substances, including paracetamol This study aimed to optimize High-Performance Liquid Chromatography (HPLC) conditions and to validate an analytical method for the determination of paracetamol in jamu for hyperuricemia obtained from Pasar Besar, Malang City. Response Surface Methodology (RSM) combined with a Box–Behnken Design (BBD) was employed to optimize the HPLC conditions. The investigated parameters were the methanol proportion in the mobile phase (X_1, 30–90% v/v), flow rate (X_2, 0.5–1.0 mL/min), and column temperature (X_3, 20–30 °C). The evaluated response variables included peak area (Y₁), resolution (Y₂), tailing factor (Y₃), and theoretical plate number (Y₄). The optimal HPLC conditions consisted of 30% v/v methanol in aquadest, a flow rate of 1.0 mL/min, and a column temperature of 25.18 °C. Method validation demonstrated satisfactory selectivity (λmax 245 nm; paracetamol retention time ± 3.33 min), linearity (r² = 0.99), limit of detection (LOD) of 1.51 ppm, and limit of quantification (LOQ) of 5.03 ppm. The method also showed acceptable accuracy (101.75–104.61%) and precision (0.53–1.59%), fulfilling the acceptance criteria. Paracetamol was detected in one jamu sample for hyperuricemia at an average concentration of 5.08% w/w. This finding indicates a violation of the Regulation of the Minister of Health of the Republic of Indonesia No. 7 of 2012 concerning the registration of traditional medicines.