REDUCING SUBSTANCES AND CREATININE 211 



Walker and Reisinger Method for Reducing Substances 



SPECIAL REAGENTS 



Standard Glucose Solutions. Prepare solns. in the range 10-100 

 mg./lOO ml. in 5 mg. steps. 



Sumner Reagent. Add 22 ml. of 10% sodium hydroxide to 10 g. 

 crystallized phenol. Dissolve in a little water and dilute to 100 ml. 

 Add 69 ml. of this soln. to 6.9 g. sodium bisulfite; then add a 

 soln. containing 300 ml. 4.5% sodium hydroxide, 255 g. Rochelle 

 salt (KNaC4H40r,.4H20) and 880 ml. 1% dinitrosalicylic acid. 

 Store in well-stoppered bottles and prepare fresh each week. 



PROCEDURE 



1. Introduce a 1.5-3.0 mm. column of tungstic acid supernatant 

 (page 198) or other unknown soln. into a capillary tube (0.35 mm. 

 inner diameter) followed by a second column (three times as long) 

 of the reagent. Seal both ends of the tube and mix by centrifuging. 



2. Mix the standard solns. with reagent in test tubes employing 

 1 ml. glucose to 3 ml. reagent. 



3. Immerse the capillary tubes and the test tubes together in 

 boiling water for 5 min. 



4. Transfer the standard color solns. to capillary tubes. 



5. Compare the colors on a white background under light 

 screened with Daylite glass. 



CREATININE 



Bordley, Hendrix, and Richards (1933) adapted Folin's method 

 for the determination of creatinine to capillary tube colorimetry. 

 As finally worked out, this adaptation enables analysis of about 0.5 

 fj}. of liquid containing 10-30 m/y.g. creatinine with an error of a few 

 per cent. For other methods see page 239. 



Method of Bordley et al. for Creatinine 



SPECIAL REAGENTS 



Standard Creatinine Solutions. Prepare solns. containing 2.0, 2.5, 

 3.0, 3.5, 4.0, 4.5, 5.0, and 6.0 milligram per cent creatinine in 0.01 

 A^ hydrochloric acid. Add toluene as a preservative. 



