[Spectrophotometric determination of enalapril maleate by bi-complex formation with bromocresol green]

ABSTRACT

We developed a new, simple, sensitive method for determination Enalapril Maleate [EM] by formation yellow complex between Enalapril Maleate and Bromocresol green [BCG]. The complex absorption maximum was at lambda max = 417 nm. The optimum conditions for complex formation were the buffer volume of HC1+KC1 0.2M for each [2-3] ml and 5 ml of Bromocresol green 1.10[-3] M which was enough for complete complex formation when the concentration of Enalapril Maleate was 10 mg/L. The linear relationship between the absorbance and the concentration of Enalapril Maleate was in the range of 5-35 mg/L, molecular molar absorsivity was 25125 L.mol[-1].cm[-1], the molar ratio [Indicator, drug] was [11]. This new method had offered a determination of Enalapril Maleate with a high accuracy and an authenticity for the analytical results. The minimal concentration could determine was 1 mg/L with relative standard deviation does not exceed 2.86%. We determined Enalapril Maleate by this method either in its raw material or pharmaceutical form without any interference with auxiliary excepients or Hydrochlorothiazide in its present case