Modelling of phase-fluorometric oxygen sensors: Consideration of temperature effects and operational requirements

A new modelling approach was developed which allows determination of optimal physical models and their parameters for phase-fluorometric oxygen sensors working in broad range of temperature and oxygen concentration. This approach was applied to two types of oxygen sensors based on platinum(II)-octyaethylporphine-ketone and polystyrene heat-treated and untreated sensors. Temperature behaviour of these sensors was examined using a range of physical models, including several new models with phase correction. Two common cases with different optimisation criteria were considered: (1) measurements at known sample/sensor temperature with minimal standard error (mean-square approximation) and (2) measurement at unknown (variable) sensor/sample temperature with minimal absolute error (uniform approximation). For each case, best models and accuracy of oxygen quantitation were determined. It was shown that heat treatment of the sensors provided improved temperature stability and better approximation accuracy within the studied temperature range.