Abstract
The Messinger-Huppert method is valuable for the determination of acetone and diacetic acid in urine but it gives only the sum of these two products and there is manifestly need of an additional quantitative method for the separate determination either of acetone or of diacetic acid.
While acetone is a liquid with a boiling point of 56°C. and dissolves in water in all proportions, I have found that it can be removed from its solutions by means of an air current and at ordinary room temperatures even more readily than ammonia. It can be determined in about half an hour, according to the same principle and by the help of the same apparatus which I use for the determination of ammonia. The determination is made as follows:
Measure 20-25 c.c. of acetone solution or urine into an aerometer cylinder and add 0.2-0.3 gm. oxalic acid or a few drops of 10 per cent, phosphoric acid, 8-10 gm. sodium chloride and a little petroleum. Connect with the absorbing bottle (as in the ammonia determination) in which has been placed water and 40 per cent. KOH solution (about 10 c.c. of the latter to 150 c.c. of the former) and an excess of a standardized solution of iodine. Connect the whole with a Chapman pump and run the air current through for 20-25 minutes. (The air current should be fairly strong but not as strong as for the ammonia determination.) Every trace of the acetone will now have been converted into iodoform in the receiving bottle. Acidify the contents of the latter by the addition of concentrated hydrochloric acid (10 C.C. for each 10 C.C. of the strong alkali used) and titrate the excess of the iodine, as in the Messinger-Huppert method, with standardized thiosulphate solution and starch.
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