DETERMINATION OF PARACETAMOL, METHYL PARAHYDROXYBENZOATE, ETHYL PARAHYDROXYBENZOATE, AND PROPYL PARAHYDROXYBENZOATE IN MEDICINAL SUSPENSION AND TABLETS BY RPLC/UV-DAD

Abstract

This paper presents a new reversed-phase liquid chromatographic (RPLC) method with ultraviolet absorbance diode-array detection (UV-DAD) for simultaneous determination of paracetamol, methyl parahydroxybenzoate, propyl parahydroxybenzoate, and ethyl parahydroxybenzoate in commercial medicinal oral suspension and tablets. The chromatographic separation is achieved with acetonitrile, tetrahydrofuran, and water in a ratio of 21:13:66 (v/v/v) adjusted to pH 3 with formic acid as the mobile phase, a Lichrosorb RP8 (150 mm × 4.6 mm, 5 µm) column, and UV detection at 249 nm. The linear range of determination for paracetamol, methyl parahydroxybenzoate, propyl parahydroxybenzoate, and ethyl parahydroxybenzoate were 25–160 µg/mL, 20–128 µg/mL, 5–40 µg/mL, and 5–32 µg/mL, respectively. The correlation coefficients are ≥0.9997 for each analyte. The mean percent relative standard deviation values for intra- and interday precision studies are <1% in each case. The applicability of the method was evaluated in commercial dosage forms analysis.