Abstract
In two papers, Hoffmann and Wynder have described an analytical method for the quantitative determination of some phenols in the smoke of cigarettes. An application on cigarette filters permitted the statement that these filters may selectively retain phenols from the smoke. It is shown here that the analytical method has a limited precision and accuracy, sufficient to ascertain the effect of selectivity, but insufficient to detect relatively small differences between filters of similar retention capacity. It is shown that the interpretation of the results given by Hoffmann and Wynder is facilitated through the introduction of the notion of ''relative phenol retention'', i. e. the quotient of the ''phenol retention" to the ''T. P. M. retention'', whereas the ''selective phenol reduction". i. e. the arithmetic difference between these two criterions, is inapt to express the capacity of specific selectivity of a given filter, especially if the pressure drop of this latter is unknown. When classifying the filters studied by Hoffmann and Wynder according to their "relative phenol retention'', one arrives at different conclusions than these authors.