CONICET | Buscador de Institutos y Recursos Humanos

The chrono-impedancimetry technique for the on-line determination of glucose concentration in a first generation glucose oxidase/carbon paste electrode has been implemented. The biosensor was polarized with a signal composed of a 900mV DC potential and a 50mVRMS AC signal at 0.4 Hz. A frequency response analyzer was used to measure the complex impedance (magnitude |Z| and phase (Ф)) of the biosensor-bulk interface. Continuous and real time measurements were performed while glucose was added to the bulk, in a concentration range of 0 to 40mM. The impedance cumulative dose-response curves were used to construct calibration curves both for impedance magnitude and phase. The best fitting was obtained with a hyperbolic equation. Four biosensors were built, and five calibration curves were obtained for each one of them. A single test measurement (unknown glucose concentration) was also obtained after each calibration procedure. Glucose concentration was estimated with the corresponding calibration curve and also measured by colorimetric technique used as reference method. One-way ANOVA test was used to evaluate repeatability. Difference between means was not statistically significant (p>0.01) for both magnitudes (|Z| and Ф). Difference between glucose estimation methods was tested with t-student analysis. The results did not show any difference (p = 0.44). Chrono-impedancimetry was proved to be a reliable method to measure glucose concentration in real time. The technique is highly repeatable and very comparable with colorimetric technique.

enviar mensaje