Simultaneous Estimation of Four Preservatives in Pharmaceutical Ointment by RP-HPLC
A simple, specific, precise and accurate reverse phase HPLC method has been developed for the simultaneous determination of preservatives (Methyl Para hydroxybenzoate, Ethyl para hydroxybenzoate, Propyl para hydroxybenzoate and Chlorocresol) in ointment. The chromatographic separation was achieved on Zorbax column, 150 mm × 4.6 mm, 5 µm, using PDA detector. The mobile phase was 50% Methanol (v:v), at a flow rate of 1.0 mL/min. All preservatives were detected at 230 nm, at 30oC temperature for column. The retention times were 2.15 min for Methyl para hydroxybenzoate, 2.70 min for Ethyl para hydroxybenzoate, 3.69 min for Propyl para hydroxybenzoate and 4.01 min for Chlorocresol, with incredibly good resolution between peaks. The method was validated according to the ICH guidelines with respect to specificity, linearity (r2 =0.999; 0.998; 0.999 and 0.998), accuracy (99 to 100.1%), precision (RSD<2%).