Abstract
The principle of the method here described depends upon the separation of ether from blood by boiling a tannic acid blood mixture and determining the amount of recovered ether by differential absorption in concentrated sulfuric acid. Obtaining the gas sample requires 5 minutes and the entire procedure, 15 minutes. The methods described in the literature are time consuming.1, 2, 3
A 30 cc. test tube is arranged in aspirator fashion. The rubber stopper is protected by a copper guard to reduce the exposure of rubber to ether vapor. Fifteen cc. of a 1 per cent tannic acid solution are put into the test tube to which 1 cc. of oxalated blood is added. The test tube is stoppered, the tube extending into the liquid is closed by means of a pinchcock and the tube extending only through the stopper is connected with a sampling tube containing concentrated calcium chloride solution covered with a generous layer of glycerol in which ether is practically insoluble. With the sampling tube under negative pressure, the blood mixture is boiled for a minute to expel all the gases dissolved in the liquid. Near the boiling point of the liquid the precipitated blood congeals and adheres to the walls of the test tube and does not interfere in any manner with the procedure. The ether which remains in the air of the test tube is very rapidly drawn into the sampler by opening the tube which extends into the liquid. It is important that this is done as rapidly as the apparatus permits to prevent the diffusion of gases. The 40 cc. sample thus obtained is transferred to the 40 cc. analyzer and the ether content determined. 4 The test tube may be readily cleaned of its sticky coagulum by washing with dilute sodium hydrate solution.
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