Microprocessor-controlled anodic stripping voltammeter for trace metal analysis in tap water

The construction and use of a portable, microprocessor controlled anodic stripping voltammeter for on-site simultaneous metal analysis of copper, lead and cadmium in tap water is discussed. The instrumental system is comprised of a programmable controller which permits keying in analytical parameters such as sparge time and plating time: a rotating cell for efficient oxygen removal and amalgam formation; and, data handling via a minicomputer or analog pen recorder. Plating and stripping potentials are controlled by a digital potentiostat; stripping is done using a staircase waveform with measurement of the current after a one msec delay. In this way charging current effects are minimized. Results of tap water analysis showed 3 plus or minus 1 (MU)g/L lead, 22 plus or minus 0.3 (MU)g/L copper, and less than 0.2 (MU)g/L cadmium for a Berkeley, California tap water, and 1-1000 (MU)g/L Cu, 1 -2 (MU)g/L Pb for ten samples of Seattle, Washington tap water. Recommendations are given for a next generation instrument system.