A computer-controlled process-FIA system for monitoring industrial bioprocesses was developed using mediator-modified enzyme electrodes. The single-line FIA system was modified by replacing the mixing coil with a flexible operating sample dilution unit. By this way, the analyzer offers automatic procedures for self-calibration 'real-time' dilution and recalibration based on the current analyte concentration. In regard to the dynamic range of the sensors, the FIA system is able to self-adapting to any analyte concentration of the bioprocess. The technique was tested for control of glucose during microbial fed-batch processes of gluconic acid production.