VALIDATED STABILITY INDICATED RP-HPLC METHOD FOR SIMULTANEOUS DETERMINATION OF METHYL SALICYLATE, CAMPHOR AND MENTHOL IN CREAM PREPARATIONS

A method for the determination of three active products in pharmaceutical preparation Rheumatizen topical cream was described. The method was based on isocratic elution of Methyl Salicylate, Camphor and Menthol on reversed phase column C8 Thermo hyperseal 250mm x 4.6mm 5µm - using a mobile phase consisting of mixture of 45% Acetonitrile: 55% (Water+0.2% Triethyl amine adjusted to pH 5 with acetic acid)at a flow rate of 1 ml/min. Quantization was achieved with Refractive index (RI) detector. Linearity of Methyl Salicylate, Camphor and Menthol was found to be from (2.4 mg/ml to 9.6 mg/ml), (0.32 mg/ml to 1.28 mg/ml) and (0.8 mg/ml to 3.2 mg/ml), with variation coefficient 0.9998, 0.997 and 0.998 respectively. The stress testing was carried out by using the solutions that had been treated with [2M NaOH, 2M HCl and 30%H2O2] and all of these solutions were leaved for 22 hours at room temperature in tightly closed containers without further heating to avoid the loss via evaporation of the analyets due to their volatility character.