Determination of Glucose by Flow Injection Analysis with Amperometric Detection at Fe(III)-(tris(3,5-dimethyl-1-pyrazolyl)borate)2 Modified Electrodes

A modified screen printed electrode with [Fe(tris(3,5-dimethyl-1-pyrazolyl)borate)2]+[FeCl4]-, installed as part of a flow injection system, was used as an amperometric detector to determine hydrogen peroxide and glucose after on-line reaction with glucose oxidase. The influence of experimental variables on sensitivity, such as the flow rate, injection volume and reaction coil length, was evaluated using a two-level factorial experimental design. Under optimal conditions, detection limits of 15 ?M and 0.5 mM for H2O2 and glucose, respectively, were obtained. A sampling rate of 60 determinations h-1 was achieved; the relative standard deviation of analytical measurements was <5.0%. The method was validated by comparing the obtained results with those provided by the enzymatic spectrophotometric method; no significant differences were observed (p < 0.05).