QUANTITATIVE-ANALYSIS OF METHYL AND PROPYL P-HYDROXYBENZOATE ESTERS IN OINTMENT PREPARATIONS BY LIQUID-CHROMATOGRAPHY ON POLY(STYRENE-DIVINYLBENZENE)

A liquid chromatography method has been developed for quantitative ana lysis of a mixture of methyl and propyl p-hydroxybenzoates in water an d fat soluble ointment formulations. The method employs a PLRP-S 8 mu m 100 Angstrom, 250 x 4.6 mm i.d. column maintained at 60 degrees C an d a mobile phase acetonitrile-potassium phosphate buffer (pH 7.0; 0.2 M)-water (35:5:60, v/v/v), at a flow rate of 1.0 ml min(-1). The analy tes were detected by UV at 254 nm. Water soluble formulations were dis solved in acetonitrile-water (40:60, v/v). Fat soluble formulations we re dissolved in hexane and extracted with acetonitrile-water (60:40, v /v). The method showed good selectivity, repeatability, reproducibilit y, linearity and recovery.