WATER-INSOLUBLE CARBONYL COMPOUNDS 71 



occurs the yellow color in the sections cannot be relied upon to be 

 specific for the groups tested. 



Albert and Leblond Use of 2,4-Dinitrophenylliydrazine Reaction 

 for Water-Insoluble Aldehydes and Ketones 



SPECIAL REAGENTS 



2,4-Dinitrophenylhydrazine Reagent. To a saturated soln. of 2,4- 

 dinitrophenylhydrazine (No. 1866 Eastman Kodak Co.) in 30% 

 alcohol, add sufficient 0.2 A^ sodium acetate to bring the pH to 

 neutrality. 



PROCEDURE 



1. Fix tissue for 48 hr. in formalin (neutralized with magnesium 

 carbonate) and wash in nmning water for 24 hr. 



2. Prepare frozen sections 10-15 fx and place in 17% alcohol 

 for 4 hr. 



3. Place sections in the 2,4-dinitrophenylhydrazine reagent over- 

 night and wash in 17% alcohol for 20 min. 



4. Carry to distilled water and mount in glycerol gelatin. 

 Result. A positive reaction is shown by a yellow color. 



Bennett Use of Seniicarl>azide Reaction for Water-Insoluble 

 Aldehydes and Ketones 



SPECIAL REAGENTS 



Acetate Buffer, Iodine, and Thiosulfate Solutions. Same as in the 



preceding phenylhydrazine test. 

 Semicarbazide Reagent. Grind 10 g. semicarbazide hydrochloride 



with 15 g. crystalline sodium acetate, take up the mixture in 100 



ml. absolute methanol, and filter. 

 Control Reagent. Same as the semicarbazide reagent without the 



semicarbazide. 



PROCEDURE 



1.-4. Follow the first four steps in the procedure for the phenyl- 

 hydrazine test, 



5. Place sections in the semicarbazide reagent. 



6. Place control sections in the control reagent. 



7. After overnight standing, wash all sections several times with 

 distilled water. 



8. Examine at unce with incident light from above. 



