A new flow-injection determination of glucose based on the redox reaction of hydroquinone with iron(III) in the presence of 1,10-phenanthroline

A new spectrophotometric flow-injection (FI) method is proposed for the det ermination of glucose based on the redox reaction of hydroquinone with iron (III). When a glucose solution containing quinone is passed through the imm obilized glucose oxidase column introduced in FI system, quinone is reduced to hydroquinone by glucose. In the presence of I,10-phenanthroline (phen), iron(III) is then quantitatively reduced by hydroquinone to iron(II) follo wed by the formation of iron(II)-phen complex (lambda(max) = 510 nm). An FI peak observed at 510 nm corresponds to the concentration of glucose. The w ide dynamic range for glucose was obtained in the range of 1 x 10(-6)-1 x 1 0(-3) mol l(-1) at a sampling rate of 24 h(-1) and the detection limit (S/N = 3) was 5 x 10(-7) mol l(-1). Relative standard deviations were 0.78, 0.4 4 and 0.23% (n = 5) for 5 x 10(-6), 5 x 10(-5) and 5 x 10(-4) mol l(-1) of glucose, respectively. The proposed method was successfully applied to the determination of glucose in control blood sera, human blood plasma and wine . (C) 2000 Elsevier Science B.V. All rights reserved.