DETERMINATION OF TRACES OF IRON BY THIN-LAYER SPECTROELECTROCHEMISTRY

The complex of iron with Chrome Azurol S (CAS) was studied using a lon g path-length thin-layer spectroelectrochemical cell with dual working electrodes. A method for the determination of traces of iron is propo sed, based on the variation in the absorbance between the oxidized and reduced state of the complex (DELTAA). DELTAA was proportional to iro n concentration over the range 0-3 mug ml-1. Compared with the convent ional spectrophotometric determination of iron using CAS, the selectiv ity was improved because the analytical signal here depended on both t he spectral and the electrochemical behaviour of the tested species. I ron was determined in water samples by this method. A concept characte rizing the sensitivity of the spectroelectrochemical signals is also p resented.