A new UPLC approach for the quantitation of ephedrine and guaifenesin in a syrup formulation using multivariate optimization strategy

A new ultraperformance liquid chromatography (UPLC) method with photodiode array detection was developed for the quantitative analysis of a commercial syrup formulation containing ephedrine (EPH) and guaifenesin (GUA). In the development of UPLC method, experimental chromatographic conditions, flow rate, column temperature, and percentage of 0.1?M H₃PO₄ in mobile phase, were optimized using chemometric multivariate strategy. From the application of a 3³ full factorial design, the optimal chromatographic conditions were obtained as the flow rate of 0.29?mL/min, column temperature of 36.4°C, and 56.9% of 0.1?M H₃PO₄ in the mobile phase. The optimal conditions gave us a good chromatographic separation of the analyzed drugs with short analysis runtime within 3?min. Calibration curves for EPH and GUA in the linear working range of 4–64 and 6–96?µg/mL, respectively, were obtained using peak areas detected at 215?nm. Performance and validity of the optimized UPLC method were estimated by analyzing independent binary mixtures, inter-day and intra-day samples, and standard addition solutions containing EPH and GUA substances. It was concluded that the proposed method was a promising approach for the quantitative determination and routine analysis of a commercial syrup formulation of the titled substances.