A New extractive spectrophotometric method for determination of rizatriptan dosage forms using bromocresol green

The ion-pair complexation using bromocresol green as reagent was performed in a buffer solution and the absorbance was measured by a spectrophotometer. The ion-pair formation conditions were optimized and the accuracy and precision of the method were calculated.Results and major conclusion: Best results were achieved by using 6 ml of the bromocresol green reagent in the presence of phosphate buffer (pH 3.0). The stoichiometry of the resulted complex was 1:1. The within-day and between-day precision values were lower than 2.9 and 1.8 percent for the calibration range of 0.5--50 and 10--100 mug/ml, respectively. The proposed method was successfully used for the determination of rizatriptan in dosage forms without any interference.