Substances that appear to be less active when ionized

10 A Substances that appear to be less active when ionized 

Similarly, it has been found (Clowes, Keltch and Krahl, 1940) that all members of a series of 30 barbiturates enter both eggs and larvae of the 

At present, there is anxiety that nitrous acid, which people consume in cigarette smoke and in preserved meats, may be uniting with secondary amines in the stomach, to form nitrosamine carcinogens (see Section 13.5 for carcinogenesis). In this connexion, it is interesting that the molecular form is the species of secondary amines that reacts fastest with nitrous acid, so that amines that are only feebly ionized at pH 2 would be the most susceptible to nitrosamine formation (Sander, Schweinsberg and Menz, 1968). These weak amines seem to be quite uncommon in the stomach contents. 

The above studies of Arenicola were simplified by the fact of the pH change having no effect on the test-organism. Less fortunate were some (better unnamed) workers who investigated the action of quinine derivatives on bacteria. They thought that they had shown that the neutral molecules were more active than the ions because these drugs became more effective as the alkalinity rose [Z. Immunitdts. (1922) 34, 194]. Unfortunately they had overlooked the ionizing effect of alkali on the bacterial receptors (see Section 10.6). 

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