Investigation of the Metal Bonding Properties of Some ARA-II Compounds Using Spectrofluorimetric Method

The metal bonding properties of some ARA-II (Angiotensin II Receptor Antagonists) compounds, such as valsartan (VAL), were investigated by using spectrofluorimetric method. Fluorescence quenching of VAL by Cu(II) was studied and optimal experimental conditions were determined. The excitation and emission wavelengths were λex= 280 nm and &lambdaem= 436 nm for the Cu(II)-VAL complex in methanol medium. The calibration curve was obtained from Stern-Volmer equation plotting to F0/F-[Cu+2] graphs and the linearity was found within the range of 0.25-2.54 μg.ml-1 for the Cu(II)-VAL complex under optimal conditions. The detection limit (LOD) and the quantitation limits (LOQ) of the proposed method for this complex were 4.96 ng.ml-1 and 16.53 ng.ml-1 respectively. The stochiometry of this complex was also determined by using the continuous variation method and the molar ratio of Cu(II):VAL was calculated as 1:1. The interaction between the valsartan in tablet form and Cu(II) in the vitamin-mineral combination tablet was investigated by applying this quenching method and obtained satisfactory results.