Rapid method for coulometric analysis using an I-Q recorder

Controlled-potential coulometric determination of plutonium

“…Iodine is rapidly adsorbed at Pt electrodes in acidic solutions of iodide salts (6)(7)(8). A maximum of approximately 1.5 X lo-' mol/cm2 is adsorbed from solutions containing as little as 2 pM NaI.…”

“…Lane and Hubbard (9) determined that the Ifrom solution is adsorbed as a neutral species, whereas F-, C1-, and Brare adsorbed as anions. Adsorbed I is removed at large positive potential ( E > 1.2 V vs. SCE in 1.0 M H,SO,) with concurrent oxidation to IO3- (7). The surface of the Pt electrode is oxidized simultaneously.…”

“…The control potential was then measured and the value recorded. The readout of the blank, V,, corrected for constant background current was calculated: ( 7 ) where tl and t2 are the first and second elapsed times, respectively. El and E2 are the voltage readouts of the integrated current at tl and t 2 , respectively.…”

“…Following the proposal of analysis using controlled-potential coulometry by Hickling in 1942, early investigations required electrolysis times in excess of one hour (1)(2)(3)(4)(5)(6)(7). These long electrolysis times initiated the development of various time-saving improvements such as predictive and empirical end-point determinations as well as cell and stirrer modifications.…”

“…Predictive end-point methods based on the exponential current decay equation eliminate the need for electrolysis to completion (4)(5)(6)(7)(8). However, the time required in calculating the integrated current value often cancels the savings in electrolysis time.…”