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Composite Biosensor for Sulfite Assay: Use of Water‐Insoluble Hexacyanoferrate(III) Salts as Electron‐Transfer Mediators
Author(s) -
Svitel Juraj,
Stredansky Miroslav,
Pizzariello Andrea,
Miertus Stanislav
Publication year - 1998
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/(sici)1521-4109(199807)10:9<591::aid-elan591>3.0.co;2-z
Subject(s) - biosensor , sulfite , chemistry , graphite , sulfite oxidase , electron transfer , electrochemistry , inorganic chemistry , cationic polymerization , nuclear chemistry , electrode , organic chemistry , biochemistry
Water‐insoluble salts of hexacyanoferrate(III) and cationic surface active agents were synthetized and used as electron‐mediators for sulfite oxidase. The biosensor was prepared from a composite consisting of modified graphite (50 % w/w) and n ‐eicosane (50 % w/w). Graphite was modified with mediators or with both mediator and sulfite oxidase for surface‐ and bulk‐modified electrode, respectively. The main advantage of biosensors with insoluble mediators is the possibility to operate at a potential of 0 mV (vs. SCE), thus less interferences are expected, in comparison to soluble hexacyanoferrate(III) where a potential of +300 mV must be used. The maximum sensitivity 7.8 × 10 −4 μA/μM was obtained for bulk‐modified biosensor, prepared from graphite modified with 5 % w/w of hexadecyltrimethylammonium hexacyanoferrate(III) and 1.25 units/mg (of graphite) of sulfite oxidase. The sensitivity of the biosensor decreased to 24 % of the initial sensitivity after one month storage in dry state at ambient temperature. The use of trehalose as an enzyme stabilization agent has led to the improved stability: 40 % of the initial stability was retained after one month.