Differential Pulse Polarography at the Static Mercury Drop Electrode

The static mercury drop electrode, SMDE, Is an Important new electrode for use In polarography. In this paper an approximate theoretical treatment of a reversible electrode process Is presented for the technique of dlfférentlal pulse polarography. The considerably different nature of the DC response at the SMDE compared to that of the conventional dropping mercury electrode (DME) toads to new factors which need to be carefully considered in analytical applications of differential pulse polarography at the SMDE. For example, the DC time dependence of t^-1/2, SMDE, vs. t^1/8, DME, for reversible electrode processes can lead to a large negative distortion term for reversible electrode processes at the SMDE which Is of opposite sign and far larger In magnitude than at the DME (reduction process assumed). Interestingly, for irreversible electrode processes the DC distortion term In differential pulse polarography at the SMDE reverts to being positive. For a quasi-reversible electrode process the DC distortion term In differential pulse polarography at the SMDE can be negative, zero, or positive depending on the parameters chosen for the experiment. Differences in DC terms are also shown to be Important In comparing differential pulse polarograms obtained at the SMDE and DME for electrode processes exhibiting phenomena related to adsorption or film formation.