Analytical Sciences

A Flow Injection System for Spectrophotometric Catalytic Determination of Copper in Plant Digests and Natural Waters

Fabiana C. CAMARGO, Elias A. G. ZAGATTO and Claudio C. OLIVEIRA

Centro de Energia Nuclear na Agricultura, Universidade de Sa ~ o Paulo, P. O. Box 96, 13400-970 Piracicaba SP, Brazil

The Cu(II)-catalyzed oxidation of 2,6-dichlorophenolindophenol (DCPI) in the reduced form by hydrogen peroxide was exploited for the development of a flow injection procedure for copper determination in plant digests and natural waters. For selectivity enhancement, a Chelex-100 resin mini-column (50 - 100 mesh) was incorporated to the manifold. The proposed system is very stable, handles about 60 samples per hour, yields precise results (RSD<2% within 5.0 and 70.0 mg l -1 Cu) and requires only 0.87 mg DCPI per measurement. Beer's law is followed up to about 100 mg l -1 Cu and the detection limit is 0.09 mg l -1 Cu (in the injectate). Baseline drift was not observed during extended (5 h) operation peri-ods. Results were in agreement with certified values of standard reference materials and recoveries within 95 and 104% (Keywords: Flow analysis, catalytic copper determination, spectrophotometry, in-line separation, chelating resin)

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