Flow injection analysis: A complementary or alternative concept to biosensors

In practical applications biosensors are often forced to operate under less than optimal conditions. Because of their construction, and the physical processes and chemical reactions involved in their operation, compromise conditions are frequently required to synchronize all events taking place. In this communication it is shown Flow Injection Analysis offers itself as a complementary facility to augment the performance of biosensors, and in many cases as an attractive alternative. Based on the argument that instead of striving to force different reactions to work under compromise conditions, it is much better to separate them, optimize them individually and let them interact with each other in harmony, selected flow-injection applications are discussed. Initially, comments are made on operating sensors in the FIA mode, while the following sections deal with selected examples of enzymatic assays, aimed either at measuring substrate concentrations, including the use of enzyme amplification schemes, or determining enzyme activities.