Accurate, continuous, real-time water quality information is becoming of paramount importance to ensure safe supplies of potable water are available, as worldwide contamination of our freshwater resources increases and we diversify our reliance on alternative water resources. Nevertheless, the acquisition of continuous reliable data for aqueous environments has proven difficult to achieve, as the majority of on-line monitoring technologies currently employed are based on direct adaptations of traditional wet laboratory methods, which were not originally designed for field or continuous monitoring applications. Consequently, they have the inherent problem of requiring strictly controlled measurement conditions, which are rarely present in the natural environment and suffer from issues such as signal drift, reagent consumption, calibration and sample pre-treatment. Seeing that consistent measurement conditions are rarely present in real world environments, direct sensor deployment often means the sensor is unavoidably exposed to a wide range of measurement conditions leading to measurement errors and invalidating the operating conditions required for reliable performance.