Abstract
A satisfactory method for the determination of the acetone bodies in blood at low levels or suitable for use with small volumes of blood has not hitherto been available. An attempt has been made to devise a method which combines the sensitivity of the iodine titration (Hubbard's Method) with the specificity of the Denigë Van Slyke method. In this method the ketone bodies are precipitated as in Van Slyke's method, this precipitate is freed from contaminating material by washing, it is dissolved in acid and is distilled with heat into alkaline iodine which can be titrated with thiosulfate. Oxidation of the ketones is carried out in a large centrifuge tube with a small volume of liquid, which allows the acetone precipitate to form with very small quantities of acetone. Barium chloride is added and the fine barium sulfate precipitate helps to prevent the loss of the acetone mercuric sulfate precipitate when decanting.
Briefly the procedure is as follows : 2 cc. of oxalated blood is lyzed with 14 cc. water in a 50 cc. centrifuge tube and 14 cc. of mercuric sulfate solution (as in the Van Slyke method 1 ) added with shaking. After standing an hour this is centrifuged and the supernatant liquid filtered. Ten cc. of filtrate∗ is placed in a special centrifuge tube with a ground glass joint and 4 cc. of a solution added which contains per 100 cc.: 70 cc. of the above mentioned mercuric sulfate solution, 20 cc. of 50% sulfuric acid, and 10 cc. of water. Connected by the glass joint to a reflux condenser this mixture is boiled for 90 minutes. As soon as boiling has commenced 0.5 cc. of 5% potassium dichromate is added.
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