154 METHODS FOR THE ANALYSIS OF BLOOD 



In case it is desired to determine separately the acetone plus 

 acetoacetic acid and the hydroxybutyric acid in a single sample 

 of blood, this may be done by first precipitating the preformed 

 acetone plus that from acetoacetic acid, and then determining 

 the hydroxybutyric acid in the filtrate. The preformed acetone 

 plus that from acetoacetic acid is precipitated exactly as in urine 

 analysis. The filtrate from the mercury-acetone precipitate is 

 received into a dry flask. After as much of the solution as possible 

 has been filtered through, and before any wash water has been 

 used, 160 c.c. of the filtrate, equivalent to rr&XS c.c. of blood, 

 are placed in a 500 c.c. Erlenmeyer flask, heated to boiling under 

 a reflux condenser, and 5 c.c. of 5 per cent potassium dichromate 

 solution are added through the condenser. The rest of the hydroxy- 

 butyric acid determination is carried out as described for urine 

 from the point where the dichromate is added. 



To calculate the acetone bodies as /3-hydroxybutyric acid 

 instead of as acetone, multiply the above factors by 1.793; to 

 calculate molecular concentration, divide the factors by 58. 



Normal blood when analyzed as described for total acetone 

 bodies yield only 1 or 2 mg. of precipitate, equivalent to 0.013 

 to 0.026 gm. of acetone per liter. In diabetics as much as 2.5 

 gms. of acetone bodies calculated as acetone has been observed, 

 while patients under ordinarily good control show 0.1 to 0.4 gm. 



CHOLESTEROL IN BLOOD OR BLOOD SERUM 



Method of Bloor 1 



Principle. The protein is precipitated with a mixture of alco- 

 hol and ether and the cholesterol in the filtrate is estimated 

 colorimetrically against a standard solution of cholesterol. 



Procedure. Preparation of the Sample. 3 c.c. of whole blood, 

 plasma, or serum are run slowly (a slow stream of drops) from a 

 pipette into about 75 c.c. of a mixture of redistilled alcohol and 

 ether (3 parts alcohol, 1 part ether) in a 100 c.c. graduated flask. 

 The contents of the flask should be kept in motion during the 

 process so that there is no clumping of the precipitated material. 

 The contents of the flask are raised to boiling by immersion in a 

 water bath (with constant shaking to avoid superheating), cooled 

 1 Bloor: Jour. Biol. Chem., 1916, 24, 227. 



