ADSORPTIVE PRECONCENTRATION FOR VOLTAMMETRIC MEASUREMENTS OF TRACE LEVEL OF IRON(III) WITH 2-(2-THIAZOLYLAZO)-4-METHYLPHENOL

This paper describes an electrochemical stripping procedure for ultratrace measurements of iron, in which preconcentration is achieved by the adsorption of a iron-[2-thiazolylazo)-4- methyl phenol] complex onto a static mercury drop electrode. Cyclic voltammetry was used to characterize the interfacial and redox behavior. For a 5 minute preconcentration time, the detection limit found was 1.8 x 10(-9) mol/l. Optimum experimental conditions were found by the use of a stirred triethanolamine (pH 8.6) solution with 2-[2-thiazolylazo- 4- methyl phenol] concentration of 1.0 x 10(-5) mol/l, a preconcentration potential of -0.46V and linear scan mode. With preconcentration for 30 sec., calibration plots for iron are linear for the 5-29mug/l range. Possible interferences by masking agents and several trace ions have been investigated. The interference of copper and uranium are eliminated by addition of CyDTA and carbonate ion respectively. Simultaneous determination of iron with copper and nickel is possible. The merits of the aforementioned procedure are demonstrated in the analysis of fresh water.