22 TECHNICAL DRUG STUDIES. 



peroxid, made by the same firm and both containing acetanilid, one 

 will deteriorate rapidly, while the other is fairly stable. The cause 

 of such apparent abnormalities has not yet been determined. There 

 are probably numerous contributing factors, but one undoubtedly 

 is the difference in the methods of manufacture. Furthermore, the 

 absence of acetanilid from a number of brands and their slow rate of 

 deterioration shows that acetanilid is not necessary to prevent or 

 retard decomposition. Hydrogen peroxid solutions containing acet- 

 anilid sooner or later develop a yellowish or brownish tint and an odor 

 resembling nitrobenzol. To what extent the presence of nitro- 

 benzol and similar agents are objectionable has not been established. 

 The Pharmacopoeia neither recognizes nor prohibits the use of 

 acetanilid as a preservative or antiseptic or otherwise, yet many 

 packages bear labels declaring the presence of acetanilid and at the 

 same time designate the article to be the pharmacopceial product, 

 an obvious inconsistency. The acetanilid is not added because of 

 its antiseptic property, as is indicated on some labels, but because 

 of its apparent inhibiting influence on deterioration. The presence 

 of acetanilid was declared in 72 samples, and found in 70. 



ACIDITY. 



The results on acidity show that a large majority of the products 

 are excessively acid. This may be interpreted that the standard 

 equivalent of 2.5 cc of tenth-normal sulphuric acid for 25 cc of the 

 solution is too exacting. By placing the upper limit at 3 cc of tenth- 

 normal sulphuric acid for 25 cc, 51 samples would still be excessively 

 acid, and by placing the standard at 4 cc, 22 would remain above the 

 limit. 



A certain amount of the acidity may be due to the oxidation of the 

 acetanilid present. This is a point, however, which should be pro- 

 vided for by the manufacturer who uses the chemical. The maximum 

 acidity prescribed by the United States Pharmacopeia does not 

 appear to be too exacting, particularly when it is remembered that 

 hydrogen peroxid solutions are largely used as mouth washes. If 

 this product should contain an excessive amount of free acid, it 

 would of necessity exert a deleterious influence upon the teeth. 



Numerous experiments have been made on the determination of 

 the acidity of hydrogen peroxid solutions by the pharmacopoeial 

 and other methods, and it has been found that methyl orange could 

 be substituted with advantage for phenolphthalein if the present 

 pharmacoposial method is retained. Experience and experiments 

 furthermore show that the free acidity can readily be determined by 

 direct titration, using phenolphthalein as indicator, and there seems 

 to be no good reason for continuing the use of the present pharma- 

 copo3ial method. 



