XJEIC ACID 213 



URIC ACID 



Bordley and Richards ( 1933) adapted Folin's ( 1930) method for 

 the determination of uric acid to capillary tube colorimetry with 

 the result that 0.03-0.5 fil. liquid containing 3-10 m/xg. uric acid can 

 be determined in solutions of known concentration with an average 

 error of about 5%. For other methods see page 239. 



Bordley and Richards Method for Uric Acid 



SPECIAL REAGENTS 



Standard Uric Acid Solutions. Prepare stock soln. containing 1 

 mg./ml. Transfer 1 g. uric acid to a 1 1. volumetric flask. Shake 

 0.6 g. lithium carbonate in 150 cc. water for 5 min. to dissolve, 

 and filter. Heat the soln. to 60°, pour into the liter flask with 

 the uric acid, and shake for 5 min. Cool under running cold tap 

 water. Add 20 ml. 40% formalin and half fill the flask with 

 distilled water. Add a few drops of methyl orange soln. followed 

 by 25 ml. 1 N sulfuric acid added slowly and with shaking. The 

 soln. should turn pink before the last 2-3 ml. acid is added. 

 Dilute to vol., mix well, and store in a tightly stoppered bottle 

 protected from light. Prepare a series of standards containing 0.6, 

 0.8, 1.0, 1.2, 1.4, 1.6, and 2.0 mg./lOO ml. 



Cyanide-Urea Solution. Dissolve 50 g. sodium cyanide in 700 ml. 

 water, add 300 g. pure urea and, when dissolved, transfer into a 

 2 1. flask. Add 5-6 g. calcium oxide and shake for 4-5 min. Filter 

 through Whatman No. 41 or similar paper. Add up to 1 g. finely 

 divided disodium phosphate; shake and filter. The soln. may be 

 used for at least 2 months if stored at room temperature and much 

 longer if kept cold. 



Uric Acid Reagent. Dissolve 100 g. sodium tungstate in 200 ml. 

 water. Add slowly with stirring and cooling 20 ml. 85% phosphoric 

 acid. Pass a slow stream of hydrogen sulfide through the soln. 

 for 20 min. but after the first 3-4 min. add 10 ml. more of the 

 85% phosphoric acid. Filter through Whatman No. 41 or similar 

 paper, refiltering the first 40 ml. Transfer the filtrate to a separa- 

 tory funnel and shake for a few min. with 300 ml. alcohol. Transfer 

 the lower layer into a previously weighted 500 ml. flask and add 

 water to a total of 300 g. liquid. Boil a few min. to remove the 



