234 PHYSIOLOGICAL CHEMISTRY 



glacial acetic acid solution of o-tolidin 1 in a test-tube add i c.c. of the solution 

 under examination and i c.c. of 3 per cent hydrogen peroxide. In the presence 

 of blood a bluish color develops (sometimes rather slowly) and persists for 

 some time (several hours in some instances). 



This test is said to be as sensitive for the detection of occult blood in 

 feces and stomach contents as is the benzidine reaction. It is also 

 claimed to be more satisfactory for urine than any other blood test. 

 The acetic acid solution may be kept for one month with no reduction 

 in delicacy. 



(c) Phenolphthalein Test. z Make a thin fecal suspension using about 5 c.c. of 

 distilled water. Heat to boiling, 3 cool and add 2 c.c. of the suspension to i c.c. of 

 the phenolphthalein reagent 4 and a few drops of hydrogen peroxide. A pink or 

 red color promptly forms in the presence of blood. 



Schirokauer 5 makes the statement that a mixture of alcohol and glacial acetic 

 acid will give the phenolphthalein reaction for occult blood. The action of an oxi- 

 dizing agent will make this reaction more distinct. Von Czylharz and Neustadl 6 

 find that a solution of sodium salicylate added to a blood-free extract of feces will 

 give a very deceptive reaction, while feces after the administration of sodium 

 salicylate by mouth gave the same reaction. The same was true of acetyl salicylic 

 acid and other similar drugs. Their studies in clinical cases likewise indicated that 

 the phenolphthalein test was unreliable. 



(d) Hematein Reaction for Occult Blood. Couturier 7 advises the use of 

 hematein 8 in testing for occult blood. It is only slightly soluble in water, 

 but gives a pronounced red color. In contact with sodium hydroxide 

 this red solution turns a deep violet blue, giving an insoluble compound 

 of hematein and sodium. This compound, exposed to the air oxidizes 

 after several days, and gives brownish or yellowish compounds, depend- 

 ing on dilution. This change is only hastened a little by the addition 

 of hydrogen peroxide, but if a trace of blood is added to the hydrogen 

 peroxide, it takes place almost instantly. To avoid oxidation, the hem- 

 atein sodium mixture should be prepared just before use. Three fluids 



1 NH 2 NH 2 



CH 3 CH 3 



2 Boas: Deut. med. Woch., 37, 62, 1911. 



8 Boas suggests using an ether extract of the fecal suspension thus eliminating the 

 necessity of boiling. However, oxidizing enzymes are the main sources of error here and the 

 action is easily and effectively eliminated by boiling. (See White: Boston Medical and 

 Surgical Journal, 164, 876, 1911.) 



4 Prepared by dissolving 1-2 grams of phenolphthalein and 25 grams of KOH in 100 c.c. 

 of distilled water. Add 10 grams of powdered zinc and heat gently until the solution is 

 decolorized. Prepared in this way the solution will not deteriorate on standing. 



5 Deutsch. med. Woch., Aug. 6, 1914. 



6 Wien. med. Woch., Sept. 5, 1914. 



7 Lyon Med., 46, 313, 1914. 



8 Hematein is a brownish-red crystalline substance derived from hematoxylin by the 

 successive action of ammonia and acetic acid. It should not be confused with hematin, 

 the hemoglobin derivative. 



