PRECISION POLAROGRAPHY BY TIME-INTEGRATION OF DIFFUSION CURRENT

A new method of measuring the polarographic limiting current is described, based on integrating it over a precisely known time interval which includes 50 or more mercury drops. The averaging effect of integration minimizes the influence of small random variations in the factors which govern the diffusion current and is conducive to high precision. The electrical instrumentation, which produces the time integral as a direct readout, is relatively simple, and all components are available commercially as complete units whose assembly requires only interconnection. Provided that the correction for any preceding diffusion currents is smaller than the one being measured, and by comparison with a standard solution, substances present at concentrations 1-10 mM are determinable with a precision and accuracy of the order of ±0.1%. © 1969.