The Proteus is a new product launched by Proteus Instruments providing users with a robust, repeatable, low maintenance sensor platform for measuring COD in real-time. The The Proteus is underpinned by comprehensive research exploring the use of in-situ fluorescence as a technique for real-time COD measurement. The Proteus (See Fig. 1) is a multi-parameter instrument that can incorporate a range of optical sensors. For COD measurement the standard configuration includes a tryptophan-like fluorescence (TLF) sensor, turbidity sensor and thermistor and can provide real-time measurement of reactive dissolved organic matter found in sewage and slurry, negating the need for COD laboratory analysis. Using a robust correction algorithm the tryptophan signal is corrected, in real time, for temperature interference. The result is a repeatable measurement that can provide instantaneous COD measurement with a simple site specific calibration for turbidity and TLF relationship with COD.