Trace Zinc Determination in Acid Media by Differential Pulse Anodic Stripping Voltammetry at a Hanging Drop Mercury Electrode

On collection, natural water samples are frequently acidified to minimize interactions of the sample and container. With dc anodic stripping voltammetry, the direct determination of zinc in acidic media is not possible because of the presence of the hydrogen ion wave, and the solution has to be buffered to higher pH. In the present work, it is demonstrated that, for a wide range of natural water systems, trace amounts of zinc can, in fact, be determined directly in acidic media by differential pulse anodic stripping voltammetry at a hanging drop mercury electrode. Avoidance of the buffer addition stage eliminates one of the greatest potential sources of contamination and permits Zn, Cd, Pb, and Cu to be determined directly and simultaneously on the acidified sample.