Development and validation of simple and rapid high performance liquid chromatographic method for routine analysis of human insulin in formulations

A simple, specific, precise and accurate reversed phase liquid chromatographic (RP-LC) method has been developed for determination of insulin in dosage form. The chromatographic separation was achieved on a Symmetry® RP-C18, (150 × 4.6 mm, 5 μm) column at a detector wavelength of 214 nm and a flow rate of 1.0 ml/min. Mobile phase comprised of 55 volume of 1 mmol sodium sulphate in high performance liquid chromatographic (HPLC) water pH 3.2, adjusted by phosphoric acid and 45 volume of acetonitrile. The retention time of insulin was 4.3 min. The linear regression analysis data for the calibration plots showed good linear relationship in the concentration range between 1 and 45 µg/ml. The value of correlation coefficient, slope and intercept were, 0.9997, 67755 and 10773, respectively. Standard deviations of the slope and intercept for the calibration curves were 1824 and 17908, respectively. Limit of detection (LOD) and limit of quantitation (LOQ) values were determined to be 0.10 and 0.25 µg/ml, respectively. The method was validated for accuracy, precision and ruggedness. Mean recovery was 100.46%, while intra- and inter-day relative standard deviations were 0.395 and 0.289%, respectively. The proposed RP-LC method can be applied for the quality control or routine analysis of bulk insulin as well as commercially available formulations of insulin.   Key words: Human insulin, isocratic, simple, rapid, high performance liquid chromatography (HPLC), pharmaceutical formulations.