Determination of Acetaminophen, Phenylephrine, and Ascorbic Acid on Zodiac HST S1 Column

his method demonstrates the simultaneous determination of Acetaminophen (a non-opioid analgesic), Phenylephrine (a sympathomimetic decongestant), and Ascorbic Acid (Vitamin C) using the Zodiac HST S1, a mixed-mode HPLC column combining reversed-phase and ion-exchange interactions. The distinct chemical properties of these compounds—neutral (Acetaminophen), basic (Phenylephrine), and acidic (Ascorbic Acid)—make separation challenging on conventional C18 columns. The Zodiac HST S1 column enables effective resolution due to its dual retention mechanisms. This method provides good peak shape, resolution, and short analysis time, making it suitable for routine quality control of cold and flu combination products.