PHOSPHORIC ACID IN BLOOD 171 



Preparation of Solutions. Magnesia Mixture. Dissolve 10 

 gms. of magnesium chloride (sticks) and 5 gms. of ammonium 

 chloride in 250 c.c. of water; add 10 c.c. of concentrated 

 ammonia. Allow to stand over night, filter, neutralize with 

 hydrochloric acid, using phenolsulfonephthalein as an indicator, 

 and make up to 500 c.c. with water. 



Standard Magnesium Ammonium Phosphate Solution. This 

 solution is made by dissolving 0.1584 gm. of air-dried magnesium 

 ammonium phosphate (MgNH 4 PO 4 .6H 2 O) in 100 c.c. of 0.1 N 

 hydrochloric acid and diluting to 1 liter with water. One c.c. of 

 this solution is equivalent to 0.02 mg. of phosphorus. 



PHOSPHORIC ACID IN BLOOD 



Bloor's Method l 



Principle. Organic material in the blood is decomposed by 

 treatment with acid. The phosphates are then precipitated as 

 strychnine phosphomolybdate and the amount is measured 

 nephelometrically by comparison with a standard phosphate 

 solution. 



Total Phosphates, Whole Blood 



Procedure. 3 c.c. of blood are measured with a pipett into 

 a 25 c.c. graduated, glass-stoppered flask, the flask is filled to the 

 mark with water, and the solution well mixed. 1 c.c. of the solu- 

 tion (equivalent to 0.12 c.c. of blood) is measured into a large 

 (200X25 mm.) test-tube, 1.5 c.c. of a mixture of concentrated 

 sulfuric and nitric acids and a few glass beads are added, 

 and the whole is heated with a micro-burner in the hood. The 

 heating is carried out in three stages. In the first stage the mixture 

 is raised to boiling and then the flame turned down until only 

 a slow but constant bubbling takes place. Heating is continued 

 at this rate until red fumes cease to come off. The time required 

 varies with the sample but ordinarily is not more than fifteen 

 minutes. In the second stage of heating the flame is increased 

 until the water is driven off and strong heating with volatilization 

 of a part of the sulfuric acid is continued for eight to ten minutes, 

 1 Bloor: Jour. Biol. Chem., 1918, 36, 33. 



