Research on fluorescence-based integrated optical immunoassay multisensing systems has gained growing interest in the last ten years. This is because the systems have the potential to simultaneously detect multiple analytes in a single measurement, and the techniques involved are fast, robust and cost-effective. Therefore they have the potential to replace conventional chromatographic techniques, as the monitoring systems for the rapid assessment of water or food samples. Other areas, such as clinical diagnostics or forensic science also have a demand for highly multiplexed analytical systems. This thesis presents a novel 32-analyte integrated optical fluorescence-based multisensor, and its integration to an automated multi-bio-sensing system. This system is primarily used for detecting organic pollutants in river water. A detailed study was also carried out with a CCD detector system, used to replace the fibre collection and photodiode array system and allow straight forward extension to more than 32 analytes. A direct comparison between these two systems is also presented