THE METABOLISM OF THE VOLATILE AMINES: III. A MICROAERATION TECHNIQUE FOR THE MEASUREMENT OF THE TWO COMPONENTS OF THE BLOOD AMMONIA LEVEL.

A microaeration technique for the measurement of the ammonia content of blood is described by means of which the amount of ammonia present in blood ("free" ammonia) can be differentiated from that which is liberated during the testing procedure by deamidating action of the alkali reagents employed. Blood is mixed with saturated potassium carbonate solution in the microaeration chamber (a bent 10-ml. pipette) and a stream of nitrogen carries the released ammonia into a collecting acid where the total ammonia liberated can be estimated at frequent intervals.A blood ammonia diffusion curve can be drawn by plotting the total ammonia diffused against the microaeration time. This is a composite curve in that it consists of the sum of an exponential curve which corresponds to the diffusion of "free" ammonia, and a relatively straight line which corresponds to the formation of ammonia by the breakdown of blood constituents. By extrapolating the linear segment back to the ordinate the quantity of ammonia initially present in the blood can be estimated. This technique is easy to learn, requires inexpensive equipment and small volumes of blood, and gives reproducible results.