Adsorptive stripping measurements of chromium and uranium at iridium-based mercury electrodes
- New Mexico State Univ., Las Cruces, NM (United States)
Iridium-based mercury electrodes are shown to be very suitable for adsorptive stripping measurements of chromium and uranium in the presence of the DTPA and propyl gallate complexing agents. The well-adhered mercury hemispherical electrode offers remarkable durability to withstand various manipulations expected under field deployment and the `pure` mercury surface essential for efficient adsorptive accumulation of the corresponding metal chelates. An electrochemical `cleaning` step ensures complete removal of the adsorbed metal chelate at the end of each run. The same hemispherical surface is thus used over a prolonged period of over five weeks, performing hundreds of runs with RSDs lower than 10%. Detection limits of 0.4 {mu}g/L uranium and 0.5 {mu}/L chromium are obtained following a 10 min adsorptive accumulation. The electrode responds rapidly to the `switching` between solutions of low and high concentrations of chromium or uranium. Proper choice of the constant current used for stripping potentiometric measurement of the uranium-propyl gallate complex results in an effective elimination of the oxygen background contribution. Various experimental parameters relevant to the mercury plating, adsorptive accumulation, and surface `cleaning` steps are explored and optimized. Applicability to groundwater and soil samples is demonstrated. 17 refs., 5 figs.
- DOE Contract Number:
- FG07-96ER62306
- OSTI ID:
- 535453
- Journal Information:
- Analytical Chemistry (Washington), Vol. 69, Issue 8; Other Information: PBD: 15 Apr 1997
- Country of Publication:
- United States
- Language:
- English
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