Determination of dissolved oxygen in water based on its quenching effect on the fluorescent intensity of bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium complex

A water-soluble fluorescence dye, bis(2,2'-bipyridine)-5-amino-1,10-phenanthroline ruthenium complex (Ru(bpy)(2)(5-NH(2)-1,10-phen)), was synthesized and used as a fluorescence probe for detecting dissolved oxygen in water. The fluorescence intensity of the probe in different dissolved-oxygen concentrations was investigated. The sensitivity of the probe was evaluated in terms of the ratio I(N(2))/I(O(2)), where I(N(2)) and I(O(2)) correspond to the detected fluorescence intensity of nitrogen and oxygen-saturated solutions, respectively. The experimental results showed that the probe yielded a linear Stern-Volmer plot, and had a I(N(2))/I(O(2)) ratio of about 5.2. The detection limit, defined as three-times the standard deviation, was 8.6 × 10(-7) mol L(-1) after eleven determinations of nitrogen-saturated blank solutions. Additionally, the probe was pH-insensitive and ionic strength-independent with good characteristics of practicality and selectivity.