M. Stredansky et al., Determination of D-fructose in foodstuffs by an improved amperometric biosensor based on a solid binding matrix, ANAL COMMUN, 36(2), 1999, pp. 57-61
An improved amperometric biosensor based on a solid binding matrix (SBM) co
mposite transducer has been used for the determination of D-fructose in foo
dstuffs samples. The enzyme, D-fructose dehydrogenase (EC 1.1.99.11), was i
ncorporated directly into a solid composite transducer containing both 2-he
xadecanone as SBM and chemically modified graphite. Hexacyanoferrate(III) w
as used as a redox mediator and the current variation caused by the presenc
e of D-fructose was measured amperometrically. The electrochemical properti
es and the characteristics of the composite fructose biosensors are describ
ed. The amperometric signals were fast, reproducible and linearly proportio
nal to D-fructose concentrations in the range 50 x 10(-6)-10 x 10(-3) mol l
(-1), with a correlation coefficient of 0.999. A set of measurements at +0.
20 V versus SCE for 2 x 10(-3) mol l(-1) D-fructose yielded a relative stan
dard deviation for the steady-state current of 2.11%. The use of a chemical
ly modified graphite by a mild oxidation step was shown to improve the bios
ensor selectivity against anionic interferents such as L-ascorbate. The bio
sensor proved to be stable for 6 months and the assay of D-fructose by this
electrode was not influenced by the presence of sugars or other interferen
ts commonly found in food samples. The biosensor was used for the determina
tion of n-fructose in some food samples, and the results were consistent wi
th those obtained with the commercially available D-fructose enzyme photome
tric kit.