A biosensor using a composite polymer to prevent interferences was use
d in a flow injection analysis system for the detection of galactose i
n human plasma. The biosensor consisted of galactose oxidase immobiliz
ed on a platinized carbon electrode that had been modified with a comp
osite polymer. The composite polymer showed improved selectivity to hy
drogen peroxide compared with either of its individual polymeric compo
nents, Nafion and a copolymer of diaminobenzene and resorcinol. The co
mposite polymer minimized the effect of possible interference from ura
te, ascorbate, and acetaminophen. This analytical system had a minimum
detection limit of 50 mu M, linearity to 6 mM, a storage stability of
greater than 30 days, and a high sample throughput (approx. 120 sampl
es/h).