Chemiluminometric enzyme sensors for flow-injection analysis

Chemiluminometric monoenzyme sensors were developed for the flow-injection analysis (FIA) of hydrogen peroxide, xanthine and hypoxanthine in the concentration range between 10−3 and 10−6 M. Both a fibre optic set-up with a photomultiplier tube (PMT) and a photodiode with an integrated preamplifier were investigated to detect the chemiluminescence. Microbial peroxidase or xanthine oxidase was immobilized covalently on a preactivated membrane, which was placed in the 7.5 μl flow detector cell. The photodiode and the PMT based H2O2 sensor achieve detection limits of 10−6 and 10−7 M, respectively. To develop bienzyme sensors for glutamate, lysine and xanthine the microbial peroxidase was coimmobilized with the corresponding oxidases on the sensor membrane. These analytes can be detected in the range between 10−3 and 10−6 M. The fibre optic H2O2 sensor was combined with packed bed enzyme reactors to determine, e.g., glucose, lactate, glutamine, glutamate, ammonia, xanthine, hypoxanthine and phosphate in the range between 10−3 and 10−7 M. On this basis a fully automated FIA set-up with 5 parallel arranged enzyme reactor channels was developed for the ondashline monitoring of animal cell cultures.