Quantitative determination of salbutamol in tablets by multiple-injection capillary zone electrophoresis

A multiple-injection capillary zone electrophoresis (MICZE) method has been developed for the assay of salbutamol in Ventoline Depot tablets (GlaxoSmithKline). In the developed method, seven sample sets, each consisting of three samples, were sequentially injected into the capillary and analyzed within a single run. This enabled a total of twenty-one sequential injections, i.e., six standards and fifteen samples, containing salbutamol and the injection marker oxprenolol. The injected sample plugs were separated by plugs of background electrolyte, through application of a short-term voltage (30 kV) over the capillary for different time periods, i.e., tPE1 and tPE2. The samples in each set were isolated from each other by partial electrophoresis for 2.35 min (tPE1), while the sample sets were separated for 10.50 min (tPE2). After the final injection, all the applied samples were subjected to electrophoresis for a time period corresponding to that in conventional single-injection CZE. The method was validated regarding linearity, accuracy, precision and robustness before it was applied to the determination of salbutamol in 15 tablets of Ventoline Depot with a labeled content of 8 mg salbutamol. The average salbutamol content was determined to 7.8 mg (±0.3 mg) from simultaneous analyses of the 15 different tablets.