Studies of medium effects on the DPASV determination of Cu in natural waters using conventional and flow-through electrodes

Abstract

A survey of DPASV signals for Cu in a variety of media and under varying conditions has been undertaken. It is possible to identify the circumstances associated with two distinct problems in Cu determination which have not been clearly distinguished in earlier literature. The role of Cl− in influencing the Hg wave form (which in turn affects the relative apparent peak heights and widths of the two Cu signals arising from Cu(Hg) amalgam and undissolved Cu(solid)) is distinguished from the role of Cl− as a complexing agent in solution at higher Cl− concentration. Effects of dissolved organic matter in natural waters are shown to resemble Cl− effects. Data are also presented on two related matters: (1) some factors in a natural water sample that confuse the use of DPASV as a tool for Cu species identification, and (2) the effects of high Cl− concentration on Cd, Pb, and Cu signals.Following the study of medium effects and interferences influencing DPASV signals, a fresh water sample has been examined at the conventional hanging Hg drop electrode, thin Hg films on graphite and Hg thin films on a novel reticulated vitreous carbon flow-through electrode. Hg thin film electrodes deposited insitu are confirmed to be very sensitive for analysis of river water samples. The flow-through electrode has excellent sensitivity. Promising storage characteristics of the flow-through electrode are evaluated with a view to suggesting an ASV system using a simple electronic unit for field sampling.