Microdialysis-bioreactor for on-line monitoring of glucose in food samples

A new microsystem, integrating microdialysis sampling and glucose oxidase immobilized on a tungsten wire inserted into the lumen of the microdialysis probe, has been developed. The microsystem, coupled with amperometric detection, has proved to be viable for glucose determination in food samples. The immobilization procedure, based on the formation of an insoluble net formed by the enzyme with a polyanhydride (in the presence of polyethyleneimine), yielded a very stable enzyme layer that maintained about 75% of its initial activity after one month of daily use. Complex sample matrices (milk, juices) were successfully analyzed with little or no sample pretreatment using the fully automated flow system.