Investigation into the practicalities of making quantitative electroanalytical measurements in frozen electrolytes

Abstract

Chronoamperometry and measurements of potential differences in frozen electrolytes were used to determine the suitability of these media for quantitative electroanalytical methods. The ice samples that we prepared appeared to consist of volumes of pristine ice crystals, more or less devoid of solute, interlaced by channels of dislocated ice crystals in which the bulk of the solute was located. At conventional electrodes, chronoamperometric currents were reasonably representative of the bulk electrolyte concentration: microelectrodes gave an enhanced response due to preferential formation of dislocated ice crystals. Cyclic voltammetry was used to investigate hexacyanoferrate, ascorbic acid and formaldehyde electrochemistry in frozen electrolytes. Electrode reactions of the chemical–electrochemical and electrochemical–chemical (EC) type were examined. The results for the EC mechanism and the straight reversible system support the view of the ice structure discussed above.