Su-Cheng Pai, Cheng-Ho Li, Brandon M. Stephens*
Oxygen is an important parameter in all environmental research topics. Although many new types of oxygen sensors have been developed recently, their precision and accuracy still heavily depend on calibration using wet chemical methods such as Winkler titration and direct iodine colorimetry. The most widely adopted colorimetric technique was developed at this institute, but it has received criticisms from other scientists, particularly regarding the isosbestic point and its susceptibility to temperature effects. The original technique, known as the Shibala procedure, has been critically reassessed and improved by incorporating temperature control during the measurement.
Cheng-Ho Li, a former M.Sc. student of this institute, and his advisor, Prof. S.C. Pai, made significant progress in deciphering the mixed spectra of molecular iodine and triiodine ions before Prof. Pai’s retirement in 2024. Prof. Stephens has since taken over the research and derived new insights into complicated iodine reactions, as well as the procedure to ensure more precise and accurate measurements.
This work was published in the American Chemical Society journal ACS Omega:
S.C. Pai, C.H. Li, B.M. Stephens* (2024) Colorimetric Determination of Dissolved Oxygen: Assessment of Methodological Influences on Iodine Spectra, Isosbestic Point, Precision, and Accuracy, ACS Omega, 9 (47), 47350-47360. DOI: 10.1021/acsomega.4c09084
