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The determination of sulfur dioxide in wines by flow injection analysis is described. The method is based on a dual electrochemical system, the upstream electrode being a coulometric electrode that eliminates interferences prior to the detection of the analyte at an amperometric electrode. At least 30 wine samples per hour can be determined by this procedure, and the results for free and total sulfur dioxide concentration in white wines compare favorably with those obtained by the standard aspiration‐oxidation, method.

A rapid and highly sensitive method using constant current stripping potentiometry for the determination of nickel and cobalt in seawaters and industrial wastewaters has been established. The method is based on the adsorptive accumulation of nickel and cobalt in the presence of either dimethylglyoxime (DMG) or or-benzyldioxime (a-BD) prior to stripping using a constant reducing current. Nitrite is used in the stripping step for the catalytic enhancement of the stripping signal. Analytical protocols for standard solutions using DMG or a-BD show good precision (RSDs between 3 and 4% on the same film) and detection limits (30ng/L for Ni/DMG; IOng/L for Co/DMG; 9ng/L for Co/cu-BD). However, iron interferes significantly with the determination of cobalt using a-BD. With DMG, the simultaneous determination of nickel and cobalt is possible and has been developed into a protocol readily applicable to the routine determination of these metals. The analytical protocol is rapid, easy to perform and the results are in agreement with those obtained by graphite furnace atomic absorption spectrophotometry. The DMG procedure has also been optimized for the determination of cobalt alone, which has advantages for determinations at concentrations of 1 pg/L or less.

A new approach to the elimination of Zn/Cu intermetallic interference in the determination of zinc by potentiometric stripping analysis is described. The method is based on the use of several enrichment/ stripping cycles, with each cycle using an enrichment time of 10 secdtlds or less and the stripping signal from each cycle being added to give the total stripping signal. The additive method compares favorably with the traditional "third element" approach based on the use of gallium, and it is demonstrated that, for an industrial sample containing oil and grease, the additive method has s i g n i a t advantages over the gallium method. The advantages of potentiometric stripping analysis in monitoring zinc in industrial wastes and the applicability of the technique to zinc speciation studies are described.