TRACE IRON DETERMINATION IN AMINOISOPHTHALIC ACID USING DIFFERENTIAL-PULSE CATHODIC STRIPPING VOLTAMMETRY AT CARBON-PASTE ELECTRODES

Application of differential-pulse cathodic stripping voltammetry using a carbon paste electrode (consisting of carbon powder and liquid para ffin) have been investigated for trace determination of iron in 5-amin oisophthalic acid (AIPA). Samples were dissolved in 1 M HCl, pH was ad justed to 4-5 after addition of EDTA. Voltammetric measurements were p erformed after filtration. No sample decomposition (mineralization) wa s necessary. The method showed a good linearity between current and co ncentration from 3 x 10(-7) to 5 x 10(-5) mol dm(-3) of iron, with a d etection limit of 3 x 10(-7) mol dm(-3) (resp. 1 ppm in solid AIPA). T he results agreed well to those obtained by atomic absorption spectrom etry (AAS) using electrothermic atomisation. For AAS measurement, howe ver, microwave digestion of samples was necessary. (C) 1998 Elsevier S cience B.V. All rights reserved.