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Rapid coulometry of tocopherols in ethanol and chloroform using ferricyanide ion mediator
Author(s) -
Uchiyama Shunichi,
Kurokawa Yuichi,
Hasebe Yasushi,
Suzuki Shuichi
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.1140060112
Subject(s) - coulometry , chemistry , ferricyanide , chloroform , electrolysis , ethanol , chromatography , electrolyte , supporting electrolyte , inorganic chemistry , electrochemistry , electrode , organic chemistry
Abstract In order to estimate the absolute determination method of tocopherols, rapid coulometry has been carried out by using a vapor grown carbon fiber electrode impregnated with ethanol‐water solution containing ferricyanide ion as a mediator. The electrolysis time of 1 × l0 −3 M α‐tocopherol in ethanol was below 30 seconds, and its current efficiency was attained to be 100.1% when an ethanol content in pH 4.0 electrolyte is 20%. Four isomers of vitamin E in chloroform were also determined by indirect coulometry in which ferricyanide solution was mixed with sample solution for 10 minutes prior to electrolysis and the current efficiencies of α‐, β‐, γ‐, and δ‐tocopherols were obtained to be 97.6, 100.5, 89.7, and 83.7%, respectively, and the relative standard deviations were below 1%.