Abstract

An optical oxygen sensor based on the phosphorescence quenching of a film of a palladium porphyrin containing a long alkyl chain [5-(1-carboxydecyl-4-pyridyl)-10,15,20-tritolylporphyrinato]palladium (PdPC10COOH), adsorbed onto an alumina plate has been developed. The phosphorescence intensity of the PdPC10COOH film decreased upon increasing the oxygen concentration, indicating that the film can be used as an optical oxygen sensing device based on phosphorescence quenching by oxygen. The ratio I₀/I₁₀₀ as a measure of sensitivity of the sensing film (I₀/I₁₀₀>3.0 indicates good sensitivity) is estimated to be 18.3, showing that the film is a highly sensitive device for oxygen. The film obeyed Stern–Volmer plots assuming a multi-site model and possessed good operational stability, reproducibility and a fast response. The response time is 26 s from deoxygenated to oxygenated conditions and 131 s for the reverse process.