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Updated: Jul 7, 2026

Synthesis and Calibration of Phosphorescent Nanoprobes for Oxygen Imaging in Biological Systems
Published on: March 3, 2010
Oxygen measurement via phosphorescence: reaction of sodium dithionite with dissolved oxygen
Zhimin Tao1, Jerry Goodisman, Abdul-Kader Souid
1Department of Pediatrics, State University of New York, Upstate Medical University, 750 East Adams Street, Syracuse, New York 13210, USA.
Abstract:
A homemade instrument for the measurement of oxygen concentration in aqueous solutions measures the decay rate of the phosphorescence of a Pd-porphyrin complex (phosphor) dissolved in the solution, which is flashed every 0.1 s with 630 nm light. The concentration of O2 is a linear function of the decay rate. The instrument is used to study the reaction of dithionite (S2O42-) with O2 at 25 degrees C and 37 degrees C. It is found that the ratio of dithionite to oxygen consumed in the reaction is 1.2 +/- 0.2 at 25 degrees C and 1.7 +/- 0.1 at 37 degrees C, suggesting a temperature-dependent stoichiometry. At both temperatures, the initial rate of O2 consumption, -d[O2]/dt, is found to be 1/2 order in S2O42- and first order in O2. This finding is consistent with a previously proposed mechanism: S2O42- <--> 2SO2- comes to a rapid equilibrium, and SO2- reacts with O2 in the rate-determining step.
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Ensuring accuracy in vital sign recordings while prioritizing patient comfort and minimizing anxiety is important.

