A stability indicating capillary electrophoresis method for analysis of buserelin

A simple and rapid stability indicating method based on capillary zone electrophoresis has been developed and validated for the analysis of buserelin (BUS). The best separations were achieved by using a bare fused silica capillary (75 m i.d.; 65.5 cm total, 57.0 cm effective length), phosphate buffer (pH = 3.00; 26.4 mM), at 35 °C. The sample was hydrodynamically injected at 50 mbar for 5 seconds; the applied voltage was 30 kV and detection was carried out by UV-absorbance at 200 nm. Method validation resulted in the following figures of merit : the method was linear in the concentration range between 0.781 and 500 g/ml (linear regression coefficient 0.9996), accuracy was between 99.3% and 100.9%, intra assay precision was between 0.3% and 1.0% and intermediate precision was between 1.0% and 2.1%. Evaluation of the specificity of the method showed no interference between excipients or products of force degradation and BUS. Under the selected conditions, separation of BUS and its degradation products was completed in less than 10 min, and BUS could be quantified after different stress conditions without any interference. The results enabled the conclusion that under thermal stress upon exposure to 90 °C BUS is degraded by first order kinetics. It was demonstrated that the method can be applied as a rapid and easy to use method for quantification and stability testing of BUS in biopharmaceutical formulations in quality control laboratories.