Determination of Parabens and their Degradation Product p-Hydroxy-Benzoic Acid in Pharmaceutical Dosage Forms by Hptlc Densitometry

Abstract

Abstract HPTLC densitometry has been developed for the determination of parabens and their degradation product p-hydroxybenzoic acid in pharmaceutical preparations. The method was used for simultaneous determination of parabens in combination:methylparaben - propylparaben, propylparaben - butylparaben and for the determination their stability in dosage forms (suspensions, ointment). The substances were separated on silica gel with fluorescence indicator in system n-pentane - glacial acetic acid (88:12, v/v). Absorbance measurements(detection of reflectance) of separated parabens was carried out “in situ” at 256 nm using single-level calibration (external standard). For the determination of p-hydroxybenzoic acid, a five-level calibration curve (external standard) was used in the concentration range of 20–100 ng/band. The results were evaluated by linear regression analysis. The relative standard deviation values (R.S.D.%) were in range 1.24–1.89 %.