Estimation of sulfolax and antimicrobial preservatives in laxative drops

A simple, fast, precise, economic, selective and accurate HPLC method for simultaneous estimation of sorbicacid, sodium picosulphate and methyl parabensodium in laxative drops has been developed and subsequently validated. Chromatographic separation was achieved using gradient elution with mix phosphate buffer pH 7.0 and acetonitrile. The column used was purospherstar C18, 5 μm, 25 cm × 4.6mm kept at 25°C with 1 ml/min flow rate using detection (PDA) at 263 nm. The retention times of sorbicacid, sodium picosulphate and methyl paraben sodium were found to be 4.6, 7.4 and 11.4 minutes respectively. The proposed method was found to be linear over a concentration range of 8-12 μg/ml for sorbic acid, 60-90 μg/ml for sodium picosulphate and 16-24 μg/ml formethyl paraben sodium respectively. The recovery was found to be 99.13-101.68% for sorbic acid, 99.81-100.21% for sodium picosulphate and 99.84-100.09% for methyl paraben sodium respectively. The limit of detection (LOD) for sorbicacid, sodium picosulphate and methyl parabensodium were found to be 0.032 μg/ml, 0.337 μg/ml and 0.131 μg/ml respectively and limit of quantitation (LOQ) for sorbicacid, sodium picosulphate and methyl parabensodium were found to be 0.097 μg/ml, 1.023 μg/ml and 0.399 μg/ml respectively. The method was validated with respect to specificity, precision, accuracy, linearity and robustness according to guidelines of ICH.