Resumen de Caracterización espectrofotométrica del sistema Cu(II): PPi, su implementación como método para la valoración de pirofosfato (PPi) en solución
M. Fe de la Torre, Vanesa Fernández Martínez, Ángel Reglero Chillón, Ignacio G. Bravo
The interaction of Cu(II) with pyrophosphate (PPi) in solution modifies the absorption spectrum of the cation. We provide here a proper description of the chemical interactions involved in the absorbance shift, identify the absorption coefficients of the species in solution and afford a model of the Cu(II)-PPi chemical system. Since the changes in the absorption spectrum are concentration dependent, we describe a new method for quantifying PPi in aqueous solutions, based on the modification of the Cu(II) absorption spectrum in the presence of PPi. Changes in absorptivity can be monitored and used to quantify PPi in solution. The determination is simple, fast and cheap. The detection limit of the method is 0.1 ìmol of PPi in the assay conditions. The presence of orthophosphate does not interfere in the determination of PPi. Furthermore, it is possible to use this method in biological systems containing proteins, nucleotides, EDTA or magnesium.
