2018 Volume 67 Issue 1 Pages 27-36
A dissolved oxygen sensor consisting of a poly(acrylamide-co-methacrylic acid) microsphere gel and tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) ([Ru(Ph2phen)3]2+) was developed. This sensor determines dissolved oxygen based on the quenching of the fluorescence (peak wavelength: 615 nm) of the Ru complex in microsphere gels that are immobilized on an ITO substrate in the presence of oxygen. The extinction ratio, defined as the ratio of the fluorescence intensity in a solution saturated with oxygen gas to that saturated with nitrogen gas, appeared to be independent of the film condition (62±7 %). A Stern-Volmer plot showed an excellent relationship between the fluorescent intensity and the oxygen concentration with R2 being higher than 0.95; the Ksv value was found to be 0.036 - 0.053. The determination of the dissolved oxygen concentration in a real sample (tap water) showed a relative error of at most 14 % to a commercially available sensor.