A non-sophisticated analytical procedure has been developed for monitoring the sum of heavy metal elements which form stronger EDTA complexes than manganese(II). It is based on complexation of the heavy metals with EDTA and a catalytic indication of its stoichiometry. The equivalence point is determined visually using the substitution reaction between Mn(II)-EDTA and heavy metal ions, followed by the Mn(II)-catalyzed oxidation of Acid Blue 45 dye with hydrogen peroxide. The method has a reasonable accuracy, uses simple test equipment and stable reagents, there are few interferences and it can be carried out by non-technical personnel. Neither preconcentration nor dilution of the sample is required and it is applicable to aqueous samples containing heavy metals down to ppm levels. Some applications to river and groundwaters are shown.
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