A NEW AMPEROMETRIC BIOSENSOR FOR FRUCTOSE USING A CARBON-PASTE ELECTRODE MODIFIED WITH SILICA-GEL COATED WITH MELDOLAS-BLUE AND FRUCTOSE 5-DEHYDROGENASE

A carbon paste modified with silica gel coated with Meldola's Blue and fructose 5-dehydrogenase was used to construct a new biosensor for fr uctose. An efficient electron transfer mediation from the reduced enzy me to the carbon paste electrode was verified, at a low applied potent ial of 20mV vs. SCE, where interfering reactions are minimized. A line ar response range for 0.1 to 0.8 mmol(-1) fructose was adjusted by the equation I=0.0150(+/-0.006)+0.618(+/-0.011) [fructose], with a correl ation coefficient of 0.999 and an rsd of 0.68% for n=7. The biosensor was used to determine fructose in sweets and fruit jellies and the res ults present good recovery, higher than 96% in both cases. A stable re sponse is observed over two months, when stored in a refrigerator, or for 300 measurements in continuous use.