ASSAY OF EXTREMELY LOW TECHNETIUM CONCENTRATIONS BY ADSORPTION STRIPPING VOLTAMMETRY AT THE HMDE AFTER REACTION WITH THIOCYANATE

In the presence of optimum amounts of thiocyanate, pertechnetate as well as technetium(IV) can be very sensitively assayed in acidic media by adsorption stripping voltammetry at the HMDE, using the differential pulse mode. The conditions for determinations down to approximately 5 multiplied by 10** minus **1**1g Tc ml** minus **1 of electrolyte are indicated. The surface-bound species has not yet been identified, but is probably a compound of one of the lower valence states of technetium. The relatively intense current signal appearing at minus 1. 27V (vs. Ag/AgCl) is observed if only technetium and thiocyanate are present in the solution together. Larger quantities of salts, e. g. chlorides and sulfates, accompanying the analyte decrease the sensitivity of the method considerably. This, however, can easily be avoided if, after electrodeposition is completed, preferably at potential of minus 0. 4V, the primary electrolyte is replaced by a pure solution of dilute acid for the stripping voltammetric step.