ADVANCED CHEMICAL PHYSIOLOGY 321 



molecule of water and becomes changed into creatinine. This reaction 

 is the best means of recognising creatine. 



EXPERIMENT V. Take about 10 gms. of fresh muscle, grind with 

 alcohol, filter, evaporate at about 50 C. Dissolve in water and divide 

 into two equal portions, a and b. To a, add 15 c.c. of saturated picric 

 acid solution and 5 c.c. of 10 per cent, caustic soda. Allow to stand 

 5 minutes and dilute to 500 c.c. Note that there is no change in the 

 colour of the solution, therefore creatinine is absent. To 6 add half its 

 volume of N. HC1 and heat in a flask fitted with a cork and glass tube 

 to act as air condenser on water-bath for five hours. Neutralise with 

 caustic soda, add picric acid solution and caustic soda, and dilute as 

 before. Note red colour, due to picramic acid. Creatinine, is now present. 

 (For other tests for creatinine see chapter on Urine.) 



Diacetyl Test for creatine. To 2 c.c. of a watery protein free extract 

 of muscle in a test tube add 2 c.c. of saturated Na 2 Co 3 solution, 6 

 drops of freshly prepared diacetyl solution and 2 c.c. of water. Immerse 

 in boiling water for 1 minute. A red colour develops. 



Diacetyl solution is prepared as follows : 1 grm. Dimethyl-glyoxime, 

 100 c.c. water and 20 c.c. cone. H 2 SO 4 are placed in a flask and slow 

 distillation is carried out until 50 c.c. collected. The solution must 

 be used fresh. 



Hypoxanthine and Xanthine. These are members of the group of 

 bodies known as the purine bodies. They are thus termed because the 

 so-called purine ring 



N C. 



I I 

 C C N 



N C N 



is the basis of their constitution, purine itself, a synthetic body being 



N=C H 



H C C NH 



or more simply C 5 H 4 N 4 . 



Hypoxanthine is 6-monoxypurine, and is represented by the formula 

 HN C=O 



H C C NH\ 



H or C 5 H 4 N 4 0. 



N C N 



Xanthine is 2, 6-dioxypurine : 



HN C=O 



1 I 

 O=^ C C NH 



|| >C-HorC 5 H 4 N 4 2 



HN C N r 



Lastly, 2, 6, 8-trioxypurine, which occurs in muscle in traces only, is 

 uric acid, C 6 H 4 N 4 O 3 . (See Chapter XV, p. 259.) 



z 



