Abstract: The present invention provides a means of measuring the concentration of ozone dissolved in water or another solvent. Small, discrete samples are sparged with air or another unreactive gas for a short period of time to measure a profile of ozone vs time in the sparge gas. The total amount of ozone in the original sample is obtained by integrating under the ozone vs time profile. A correction may be made for ozone remaining in the sample after a finite sparge time by integrating under the profile tail using a decay constant obtained from the measured ozone vs time profile. The method differs from previous methods based on sparging of the sample in that a Henry's Law equilibrium or constant ratio of ozone present in the gas and liquid phases is not assumed and the flow rates of sample and sparge gas are not continuous.

Abstract: The present invention provides a means of greatly reducing or eliminating the interferences of UV-absorbing compounds, mercury, water vapor and particulates in the UV absorbance measurement of ozone by replacing the internal solid-phase ozone scrubber with a gas-phase scrubber. Reagent gases well suited as a gas-phase scrubber of ozone include nitric oxide and bromine atoms. Nitric oxide may be supplied by a gas cylinder or by photolysis of either N2O or NO2, both in the absence of oxygen. Bromine atoms are conveniently generated by photolysis of Br2 supplied by a permeation tube. Bromine atoms have the advantage of having a faster reaction with ozone than NO and of being catalytic in their reaction. Nitric oxide has the advantage of being generally less reactive with other components of air.

Abstract: The concentration of nitric oxide in a gas is determined by oxidizing NO to NO2 and then measuring the concentration of NO2 in the gas, which is proportional to the concentration of NO. Preferably, gaseous NO2 molecules diffuse through a plurality of capillary membrane fibers and undergo a chemiluminescent reaction with a reagent flowing within; the light from the reaction is measured to determine NO2 concentration. In another aspect of a preferred embodiment, gas is passed through a scrubber before the concentration of NO2 is measured, in order to substantially remove carbon dioxide and ambient NO2 from the gas without substantially affecting the concentration of nitric oxide therein.

Abstract: A detector for detecting and measuring nitric oxide. Gas-permeable capillary membrane fibers transport a reagent solution through a plenum containing gases to be measured. Nitric oxide molecules penetrate the walls of the fibers and undergo a chemiluminescent reaction within. The fibers and the plenum are translucent, allowing photons emitted by the chemiluminescent reaction to escape and be detected by a photodetector. The reagent is buffered at an alkaline pH and mixed with the enzyme carbonic anhydrase to minimize the measurement errors caused by the presence of carbon dioxide in the gas to be measured.