Simultaneous determination of regular insulin and insulin aspart by capillary zone electrophoresis and application in drug formulations

A rapid and simple capillary zone electrophoresis (CZE) with ultraviolet detection has been developed for simultaneous determination of regular insulin and insulin aspart in bulk and commercial injection dosage forms. The simultaneous analysis of the tested drugs was performed in phosphate buffer (80 mM; pH 6.5). The separation of regular insulin and insulin aspart was achieved at 13 kV and detection at 200 nm within 7 min with RSD for the absolute migration time reproducibility of less than 3.8% (n = 10). Selectivity, linearity, precision, accuracy, limits of quantification (LOQ) and limits of detection (LOD) were evaluated as the method validation. Calibration plots were linear (r > 0.999) over a range of 2.0–60.0 μg/mL for regular insulin and insulin aspart. The LOD were all 1.0 μg/mL (signal-to-noise ratio = 3; injection 6.89 kPa, 7 s). The small amount of sample required and the expeditiousness of the procedure can be an advantageous alternative to traditional methodology for the quantification of tested drugs in individual pharmaceutical products.