DEVELOPMENT AND VALIDATION OF A HPLC METHOD FOR THE SIMULTANEOUS DETERMINATION OF BROMHEXINE, CHLORPHENIRAMINE, PARACETAMOL, AND PSEUDOEPHEDRINE IN THEIR COMBINED COLD MEDICINE FORMULATIONS

A simple and efficient liquid chromatographic method has been developed and validated for the simultaneous determination of bromhexine, chlorpheniramine, paracetamol, and pseudoephedrine in common cold medications (tablets and syrups). The separation of the analytes was achieved within 10 min, employing a mixture of 10 mM triethylamine-phosphoric acid buffer (pH 4.0) and MeOH (35:65, v/v) as isocratic mobile phase, pumped at 1.0 mL min−1 through a cyano column (5 µm particle size). The analytes were detected at 215 nm. Statistical experimental designs and graphic representations (response surface methodologies, Pareto charts) were used for selecting the proper detection wavelength, optimizing the mobile phase composition, and assessing method robustness. The linearity of the calibration (r > 0.99, n = 21) in the relevant ranges (up to 130% of the expected concentrations of the analytes in the formulations), method accuracy (bias < 2.0%), repeatability (RSD < 2.0%) and intermediate precision, were verified. In addition, specificity (peak purities with photodiode array detector >0.9997) and method robustness were evaluated, and system suitability parameters were determined. The validated method was successfully employed for the routine analysis of various commercial tablet and syrup pharmaceutical preparations against the common cold, showing satisfactory analyte recoveries and RSD values.