Clinical Chemistry, Vol 11, 512-520, Copyright © 1965 by the American Association for Clinical Chemistry

Closed-System Apparatus for Aeration-Diffusion: Application to Determination of Blood Ammonia

¹ 47 Raymond St., Falmouth, Mass. 02540.

An apparatus is proposed primarily for comparison with other methods for determination of "blood ammonia," and studies of involved factors. It employs the aeration-diffusion method of Van Slyke and Cullen, but in a closed system which avoids loss of ammonia and contamination with ammonia from the outside. Incomplete liberation of ammonia is avoided by the use of a moving thin film ever renewed in the donor section, and incomplete absorption of ammonia in the receiver is avoided by recirculating the air. Because the aeration may be done at any reduction in pressure, the apparatus lends itself to use in studies of the dynamics of aeration-diffusion of ammonia and other gases. A curve is presented which reconfirms the observation that ammonia liberated from blood after addition of reagents increases after 15 min. To avoid such increase, the time between blood collection and analysis is reduced to less than 2 min. A tentative upper limit of normal is set at 0.14 mg./100 ml.