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Liquid chromatography/electrochemical detection of hydroxylamines by oxidation at a cobalt phthalocyanine chemically modified electrode
Author(s) -
Qi Xiaohe,
Baldwin Richard P.
Publication year - 1994
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.1140060502
Subject(s) - hydroxylamine , amperometry , electrolysis , chemistry , electrochemistry , inorganic chemistry , hydrazine (antidepressant) , electrode , glassy carbon , cyclic voltammetry , cobalt , chemically modified electrode , nuclear chemistry , working electrode , organic chemistry , chromatography , electrolyte
Chemically modified electrodes (CMEs) containing a polymeric cosating of cobalt phthalocyanine (CoPC) were shown to catalyze the electrooxidation of hydroxylamine (NH 2 OH) and its N‐mono‐, N,N‐di‐, and O‐substituted derivatives. All of these compounds were oxidized at unmodified glassy carbon electrodes only at potentials higher than +1 V (vs. Ag/AgCl) but gave substantial anodic currents between +0.25 and +0.55 V at the CoPC‐coniaining surface. On the basis of exhaustive electrolysis experiments, the number of electrons transferred for the oxidations was found to vary between 1.2 and 1.6 depending on the particular hydroxylamine compound and the specific condition, of the electrolysis; and the products included oximes, azoxy compounds, and dimeric species. These observations were consistent with an electrocatalytic mechanism involving oxidation of the hydroxylamine by electrogenerated Co(III)PC and subsequent reaction of the initially formed oxidatior products by several pathways. When the CoPC CME was used as the sensor in amperometric detection following liquid chromatography, the detection limits obtained at +0.55 V ranged from 0.4 pmol for hydroxylamine itself up to 40 pmol for N,O‐dimethylhydroxylamine. By maintaining the applied potential at +0.20 V, the detection could be made selective for hydroxylamine and N‐mono‐substituted hydroxylamine compounds only.