Luminescence ratiometric oxygen sensor based on gadolinium labeled porphyrin and filter paper

A fluorescence-phosphorescence ratiometric oxygen sensing system based on gadolinium labeled hematoporphyrin monomethyl ether (Gd-HMME) and filter paper was developed. A compact and simple measurement system was constructed utilizing fiber optoelectronic sensing device. Optical parameter (OP) was defined as the ratio of filter paper background fluorescence to oxygen sensitive Gd-HMME phosphorescence. We demonstrate that the OP is independent of excitation intensity in this ratiometric method. The measured results of oxygen concentration were calibrated and displayed by a Labview-based software. The fluctuation is about 0.1% for a wide range of oxygen concentration above 10% and much less than 0.1% for oxygen concentrations lower than 3%. A detection limit of 0.01% was achieved. The response time was determined to be about 4 s. These results indicate that the system we have developed can be used for oxygen detection in the whole range and is especially accurate for very low oxygen concentrations.