ABSTRACT
A simultaneous microdetermination of iron and copper at sub-µg/L level by solid phase derivative spectrophotometry has been developed. The compounds TPTZ (2,4,6-tripyridyl-1,3,5-triazine) and Neocuproine (2,9-dimethyl-1,10-phenanthroline hydrochloride), were used as chromogenic reagents to form a blue iron complex and an orange copper complex, respectively (pH = 5.0), which are fixed and concentrated on a cation-exchange resin sephadex sp C-25. The influence of experimental variables on the retention of the complexes on the resin are discussed. The signals in derivative units were measured directly on the solid, packed in a 1 mm spectrophotometric cell. The characteristic amplitude of the signals at 622.0 and 477.0 nm in third-derivative spectra are useful for quantitative determination of iron (0.195–120 ng mL−1; RSD = 1.8%) and copper (0.451–300 ng mL−1; RSD 1.3%). The method was applied to the iron and copper determination in different types of water, respectively.
ACKNOWLEDGEMENTS
The authors are grateful to the National Fund for Development of Science and Technology (FONDECYT), project N° 1990033 and DID of the University of Chile I001-98/2.