Analytical and Mechanistic Aspects of the Electrochemical Oxidation of Keto Steroids Derivatized with Phenyihydrazine (4-Nitrophenyl)hydrazine, and (2,4-Dinitrophenyl)hydrazine

Alan M. Bond, Anthony F. Hollenkamp, Stephen B. Thompson, Anthony R. Bourne, Peter A. Huf, Thomas G. Watson

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The electrochemical oxidation of biologically Important 3- and 17-keto steroids derivatized with phenyihydrazines has been Investigated at platinum and glassy carbon electrodes In aqueous methanol. The oxidation process has been used In the amperometric detection of keto steroids In nonmammallan biological fluids after separation by reverse-phase liquid chromatography. The derivatization was shown to be quantitative, and the response linear with the detection limit of 1–5 ng for Injection volumes of 20 μL. Voltammetric studies on various nltro derivatives of phenylhydrazine and their corresponding phenylhydrazones show that the oxidation process occurs at the hydrazine moiety and not the nltro group. Coulometrlc data Indicate the occurrence of a two-electron transfer and mass spectroscopic evidence Indicates that the Immediate product Is a diazene which reacts with methanol. Chemical oxidation and polymerization of the products occur If the electrochemlcally oxidized solution Is left exposed to the atmosphere. The mechanism proposed for the underlvatlzed phenyihydrazines Is then RNHNH2→ RN=NH + 2H++ 2e~-→; further products, with a related mechanism applying for oxidation of steroid hydrazones.

Original languageEnglish
Pages (from-to)1023-1027
Number of pages5
JournalAnalytical Chemistry
Issue number10
Publication statusPublished - 1 May 1988
Externally publishedYes

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