A new HPLC method for the simultaneous determination of acetaminophen, phenylephrine, dextromethorphan and chlorpheniramine in pharmaceutical formulations

Acetaminophen, phenylephrine, dextromethorphan, and chlorpheniramine are frequently associated in pharmaceutical formulations against the common cold. A new high performance liquid chromatography ( HPLC) method has been developed for the simultaneous determination of these active pharmaceutical ingredients in pharmaceutical formulations. The separation and quantitation were achieved on a 25 cm underivatized silica column using a mobile phase of methanol: water ( containing 6.0 g of ammonium acetate and 10 ml of triethylamine per liter, pH adjusted to 5.0 with orthophosphoric acid), 95:5%( v/v). Detection was carried out using a variable wavelength UV-vis detector at 254nm for acetaminophen, at 220nm for phenylephrine, and at 227nm for dextromethorphan and chlorpheniramine. The method showed linearity for the acetaminophen, phenylephrine, dextromethorphan, and chlorpheniramine in the 162.5-650, 2.5-10, 7.5-30, and 1-4 mu g/ml ranges, respectively. The intraday and interday RSDs ranged from 0.92 to 1.52%, 1.00 to 1.76%, 1.21 to 1.74% and 1.26 to 1.80% for the acetaminophen, phenylephrine, dextromethorphan, and chlorpheniramine, respectively. Compounds were eluted in a run time of less than 12 min.