Expired Air Samples Research Articles

CHANGES IN CONCENTRATION OF GASES IN THE RUBBER BLADDERS OF MAX-PLANCK RESPIROMETERS.

Changes of concentration of CO2 and O2 through rubber bladders were determined by a) exposing the bladders to atmospheric air, b) putting them into polythene bags and inflating the bags by 1) normal expired air and 2) by the same gas mixture as inside the bladders. Two different gas mixtures (of similar percentage composition to that of expired air samples obtained during light and moderate exercise) were used. The rate of diffusion was found to depend on the partial pressure gradient across the rubber wall and the type of gas. The higher the partial pressure gradient, the more rapid was the diffusion, and CO2 diffused at a higher rate than O2. Such a simple procedure as putting the bladders into polythene bags and inflating the bags by the operator's own expired air was found to reduce the change of concentration considerably. A correction can be utilized to obtain a more accurate gaseous percentage composition if there is a delay between the experiment and the gas analysis. carbon dioxide; oxygen; diffusion of gases; indirect calorimetry Submitted on October 17, 1963

An improved technique for assay of C14O2 in expired air using the liquid scintillation counter.

Abstract A rapid and efficient system is described which facilitates the analysis of C 14 O 2 in large samples of expired air. The method employs a modification of the method of Passmann, Radin, and Cooper, 2 using methylbenzethonium chloride (Hyamine-10-X) for solubilization of carbonate in toluene. The initial step involving trapping in aqueous base has been eliminated. Radioactivity is measured in a liquid scintillation spectrometer. The total C 14 O 2 radioactivity and specific activity in air from a human expiring less than 1 × 10 −6 mc. per minute may be accurately measured with a minimum of time and manipulation. The direct trapping and analysis of carbon dioxide expired by small animals is also described.

Rapid CO2 determination with the Beckman O2 analyzer.

ConclusionThis method offers a simple quick technic for separate expired air samples. Both CO2 and O2 analysis may be completed within 5 minutes as compared to 15-20 minutes by Haldane. Ninety-five per cent of the duplicate CO2 analyses as determined with the Beckman C model (110-160 mm Hg range) will agree within 0.10% with duplicate Haldane data. A Beckman instrument of a narrower range and/or greater sensitivity would improve this accuracy. In our experience the Beckman C model (110-160 mm Hg range) allows better results than does the more elaborate and expensive E-2 model.