ALUMINUM PYROCATECHOL VIOLET REACTIVITY WITH VARIOUS COMPLEXING AGENTS

A spectrophotometric method for determining the speciation of aluminum using pyrocatechol violet (PCV) is tested on a series of known ligand s over a range of concentrations and at two fixed pH values. The proce dure assumes that the colorimetric signal is defined by the competitio n of the Al-ligand complex with Al-PCV. The stability constants determ ined are in agreement with literature values. Time to steady state is more than 10 min. A procedure for determining the conditional stabilit y constant, the total ligand concentration and the reactive Al at a fi xed pH is proposed.