Enhancement of Anodic Response for DMSO at Ruthenium Oxide Film Electrodes as a Result of Doping with Iron(III)
✍ Scribed by Brett K. Simpson; Dennis C. Johnson
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 150 KB
- Volume
- 15
- Category
- Article
- ISSN
- 1040-0397
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✦ Synopsis
Abstract
The oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO~2~) is representative of numerous anodic oxygen‐transfer reactions of organosulfur compounds that suffer from slow kinetics at noble metal electrodes. Anodic voltammetric data for DMSO are examined at various RuO~2~‐film electrodes prepared by thermal deposition on titanium substrates. The response for DMSO is slightly larger at RuO~2~ films prepared in a flame as compared with films prepared in a furnace; however, temperature is more easily controlled in the furnace. Doping of the RuO~2~ films with Fe(III) further improves the sensitivity of anodic response for DMSO. Optimal response is obtained at an Fe(III)‐doped RuO~2~‐film electrode prepared using a deposition solution of 50 mM RuCl~3~ and 10 mM FeCl~3~ in a 1 : 1 mixture of isopropanol and 12 M HCl at an annealing temperature of 450 °C. The Levich plot (i vs. ω^1/2^) and Koutecky‐Levich plot (1/i vs. 1/ω^1/2^) of amperometric data for the oxidation of DMSO at an Fe(III)‐doped RuO~2~‐film electrode configured as a rotated disk are consistent with an anodic response controlled by mass‐transport processes at low rotational velocities. Flow injection data demonstrate that Fe(III)‐doped RuO~2~‐film electrodes exhibit detection capability for methionine and cysteine in addition to DMSO. Detection limits for 100‐μL injections of the three compounds are ca. 3.2×10^−4^ mM, i.e., ca. 32 pmol.