Determination of paracetamol and its main impurity 4-aminophenol in analgesic preparations by micellar electrokinetic chromatography

A micellar electrokinetic chromatographic (MEKC) method was developed for the quality control of paracetamol containing pharmaceutical preparations. The influence of several factors (surfactant concentration, buffer concentration, pH and applied voltage) was studied during development and optimisation of the method. Phosphate buffer (pH 9.0) containing sodium dodecyl sulphate (75 mM) was found as the ideal running buffer for the separation; the applied voltage was 25 kV and the analysis time was 10 min. The limit of quantitation for 4-aminophenol was 6 μg ml−1; the linearity of the method was studied in the concentration ranges 20–260 μg ml−1 for paracetamol and 20–150 μg ml−1 for 4-aminophenol. The method was successfully applied for the quality control of paracetamol containing products.