Validation of a New Spectrophotometric Method for the Assay of Bisoprolol Fumarate using Tropaeolin

A spectrophotometric method for the assay of bisoprolol fumarate was established based on an ion pair complex formed between bisoprolol and tropaeolin 00, in acidic medium, which could be quantified after being extracted in dichloromethane, by measuring its maximum absorbance at 412 nm. The working procedure was established and the analysis method was validated. Thus, 1 mL 0.05M hydrochloric acid and 1 mL of 0.01% tropaeolin 00 aqueous solutions were added to 1.0 mL bisoprolol fumarate solution. Fifteen minutes later the absorbance was measured at 412 nm, using as reference a blank sample prepared in the same conditions. The method presented a good linearity in the range 5-30μg·mL-1 and the correlation coefficient was r = 0.9995. The limit of detection (LOD) was 0.67μg·mL-1 and the limit of quantification (LOQ) was 2.23μg·mL-1. The relative standard deviation for the precision of the method was 0.78. While studying the accuracy of the method a mean recovery of 100.3 % was established. The experimental data obtained showed a good sensitivity of the method and the obtained value of the specific absorbance for this method was much higher than that of the corresponding bisoprolol solution in the UV.