Analytical Application of High Frequency, Phase-Sensitive Short Controlled Drop Time Alternating Current Polarography

In general, polarographic methods do not have the specificity for the interference free direct determination of elements in complex mixtures nor are they often sufficiently rapid to be competitive with other techniques. This paper describes the analytical use of rapid, short controlled drop time, high frequency, 3-electrode, phase-sensitive ac polarography. The use of high frequencies (500 to 1000 Hz) instead of the usually recommended low frequencies, (10 to 100 Hz) can provide considerable discriminaiion against unwanted electrode processes. The medium for dissolution of many samples prior to their determination is often acidic, and in such media, and with the technique proposed, removal of oxygen is often unnecessary. This plus the use of short controlled drop times and fast scan rates of potential, provide a route to an attraciive method of analysis having a time scale close to that for atomic absorption spectrometry, linear calibration curves over several orders of magnitude of concentration, ready checks on interference, and other useful features. The determination of tin and a comparison of results with those obtained independently by several other laboratories using Atomic Absorption Spectrophotometry, X-Ray Fluorescence, and Colorimetric methods is given, to demonstrate the usefulness of the method. Other examples are also given—the determinations of U, Pb, and Cu.