tmiC ACID, CREATINE, CREATININE, AND ALLANTOIN 243 



Sure and Wilder Method for Creatine and Creatinine 



SPECIAL REAGENTS 



Saturated Picric Acid. 



10% Sodium Hydroxide (carbonate free). 



PROCEDURE 



1. Pipette 1 ml. of sample (blood filtrate) into a 15 ml. centri- 

 fuge tube and add 0.5 ml. picric acid soln. 



2. To convert creatine to creatinine, cover the tube with lead foil 

 and autoclave for 40 min. at 20 lb. pressure. Omit this step for 

 preformed creatinine. 



3. Cool, add 0.1 ml. of the sodium hydroxide, and allow to stand 

 for 10 min. 



4. Run a control on the reagents alone. 



5. Using the Evelyn photoelectric colorimeter, set the control at 

 100 with filter 520-M, and then obtain readings of the unknown. Do 

 not allow the plungers to remain in contact with the soln. for longer 

 than 1-2 min. in order to avoid corrosion. 



6. Obtain values from a previously established calibration curve. 



Borsook Method for AUantoin 



SPECIAL REAGENTS 



Enzyme Powder. Use urease preparation (Squibb) from soy bean 

 meal (Van Slyke and Cullen, 1914). 



Ammonium Carbonate-Sodium Cyanide. Dissolve 1.153 g. ammo- 

 nium bicarbonate, 0.891 g. ammonium carbonate, and 0.46 g. 

 sodium cyanide in water and make up to 200 ml. 



10% Trichloroacetic Acid. 



2% Sodium Tungstate. 



N/15 Sulfuric Acid. 



0.5% Phenylhydrazine Hydrochloride in A^/14 hydrochloric acid. 

 Dissolve commercial phenylhydrazine hydrochloride in water and 

 decolorize by boiling with activated charcoal. Filter the hot solu- 

 tion, and, after the filtrate is cooled in an ice-salt bath, precipitate 

 the phenylhydrazine hydrochloride by addition of cone, hydro- 

 chloric acid, or by dry hydrochloric acid gas. Filter the precipitate 

 off by suction; wash once quickly with very cold hydrochloric acid, 



