OxyFile #182

UI  - 94052349
AU  - Kanofsky JR
AU  - Sima PD
TI  - Singlet-oxygen generation at gas-liquid interfaces: a significant
      artifact in the measurement of singlet-oxygen yields from
      ozone-biomolecule reactions.
AD  - Medical Service, Edward Hines, Jr., Department of Veterans
      Affairs Hospital, Hines, IL 60141.
AB  - Several ozone-biomolecule reactions have previously been shown to
      generate singlet oxygen in high yields. For some of these
      ozone-biomolecule reactions, we now show that the apparent
      singlet-oxygen yields determined from measurements of 1270 nm
      chemiluminescence were artifactually elevated by production of
      gas-phase singlet oxygen. The gas-phase singlet oxygen results
      from the reaction of gas-phase ozone with biomolecules near the
      surface of the solution. Through the use of a flow system that
      excludes air from the reaction chamber, accurate singlet-oxygen
      yields can be obtained. The revised singlet-oxygen yields (mol
      1O2 per mol O3) for the reactions of ozone with cysteine, reduced
      glutathione, NADH, NADPH, human albumin, methionine, uric acid
      and oxidized glutathione are 0.23 +/- 0.02, 0.26 +/- 0.2, 0.48
      +/- 0.04, 0.41 +/- 0.01, 0.53 +/- 0.06, 1.11 +/- 0.04, 0.73 +/-
      0.05 and 0.75 +/- 0.01, respectively. These revised
      singlet-oxygen yields are still substantial.
LA  - Eng
SO  - Photochem Photobiol 1993 Sep;58(3):335-40