Determination of dissolved N₂ in blood by gas chromatography and (a-A)N₂ difference

¹ Department of Physiology, The University of Buffalo School of Medicine, Buffalo, New York

By combining vacuum extraction in a Van Slyke chamber and separation of the extracted gases in a gas chromatograph, it is possible to determine N₂ content of 1.5 ml of blood or other biological fluids in less than 10 min. The 95% confidence limits are 0.44% on either side of the mean of the triplicate analysis-or 2.4 mm Pn₂ in arterial blood when breathing room air. Application of the method to the problem of arterial-alveolar N₂ difference yielded the following data: 1) N₂ solubility in whole blood at 37.3 C varied from 0.0125 to 0.0129; 2) N₂ solubility in urine is inversely related to urine specific gravity, confirming Klocke and Rahn's data; 3) changes in arterial N₂ content were reflected in arm superficial venous blood and urine N₂ only after a considerable period of time, indicating that either of these will give an excellent indication of the mean Pn₂ over a period of time; 4) there is no systematic difference between venous blood and urine Pn₂; 5) the (a-A)N₂ difference in nine normal subjects varied from 3.7 to 13.1 mm Hg.

Note:
(With the Technical Assistance of M. Passke)