ORTHO-TOLIDIN AS AN INDICATOR FOR OCCULT 



BLOOD 



R. F. RUTTAN and R. H. M. HARDISTY 

 (Chemical Lahoratory, McGill University, Montreal, Canada) 



The authors have lately called attention to the advantages of 

 o-tolidin over benzidin and phenolphthalin as a clinical reagent for 

 the detection of occult blood.^ 



The properties and derivatives of o-tolidin, 



(4) NH (I) (I) NH, (4) 

 \c H r H / 



(2) CH/ \CH3 (2) 



were first described by one of the writers in 1886.2 This substance 

 was compared with guaiacum, benzidin and phenolphthalin in aque- 

 ous Solutions of blood and in Solutions containing urine, stomach 

 Contents, and feces. It was found to be a very delicate reagent for 

 the detection of blood in aqueous Solution, and to have some impor- 

 tant advantages over the other clinical reagents when used in the 

 detection of blood in excretions and secretions. The reagents were 

 made up as follows: Guaiacum, i in 25 methylated spirits; benzidin 

 and o-tolidin, in Solutions of similar strength, in glacial acetic acid ; 

 phenolphthalin, prepared as recommended by Kastle.^ 



The Solutions to be tested were made up from a o.i per cent. 

 Solution of cry stalline hemoglobin in water. The hydrogen per- 

 oxide Solution employed was made up to approximately 3 per cent. 

 from Merck's perhydrol. In testing, i c.c. of the reagent, i c.c. of 

 the Solution to be tested and i c.c. of diluted perhydrol were em- 

 ployed. 



In aqueous Solution, as the average of ten tests, it was found 

 that guaiacum detected blood, i in 50,000 ; benzidin detected blood, i 

 in 700,000; o-tolidin detected blood, i in 7,000,000; phenolphthalin 

 detected blood, i in 10,000,000, or even in greater dilutions. 



^ Ruttan and Hardisty : Canadian Medical Association Journal, Nov., 1912. 

 ^ Ruttan : Proccedings of the British Association for the Advancement of 

 Science, 1886. 



^ Kastle : Bulletin 51, Hygienic Laboratory, Washington, D. C. 



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