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 λem= 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.
Keywords: Valsartan, Cu(II) complex, fluorescence quenching, pharmaceutical analysis.
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