Development and validation of a rapid capillary electrophoresis method for the determination of oseltamivir phosphate in Tamiflu and generic versions.

A rapid and reliable capillary zone electrophoresis method was developed and validated for the assay of oseltamivir phosphate in capsules. Separation was carried out in fused silica capillary (60.2 cm total length and 10.0 cm effective length, 75 microm i.d.) by applying a potential of -15 kV at 25 degrees C. The selected electrophoretic buffer consisted of 50 mM sodium phosphate, pH 6.3 (direct UV detection, 226 nm). A short electrophoretic analysis time (less than 1.5 min) was obtained using the short end injection mode. The method was validated in terms of specificity, linearity, precision and accuracy. The RSD values were 0.94 and 0.98% for repeatability and intermediate precision, respectively. Recovery determinations allowed the calculation of a confidence interval from 98.64 to 100.26% with a relative standard deviation value of 0.38%. LOD and LOQ were estimated at 0.97 and 3.24 microg/mL, respectively. The validated method was successfully applied to the determination of oseltamivir in three commercially available capsules (Tamiflu, Saiflu and Flufy). The results were in good agreement with those obtained by a HPLC method previously developed in our laboratory. This method presents advantages including short run time, simple and rapid sample preparation and no use of non-aqueous solvent throughout the analysis.