The determination of higher fatty aldehydes in tissues.

The determination of the content and distribution of the higher aliphatic aldehydes in tissues have depended on modifications (l-3) of the Feulgen procedure which employs the fuchsin-sulfurous acid reagent. However, several observers, notably Ehrlich et al. (2), have commented on two features of this procedure which make its application difficult: The Schiff reagent reacts with a wide variety of compounds other than aldehydes, and the presence of excess lipides in the sample interferes with the color development. Accurate determinations are limited, therefore, to tissues rich in acetal phosphatide. While the metabolism of the higher fatty aldehydes was being investigated, it became evident that a more satisfactory method for their determination was required. A study of the reaction of p-nitrophenylhydrazine with tissue lipides demonstrated that the aldehydes are liberated from the lipides as their p-nitrophenylhydrazones. This made possible a new and specific method for the determination of the higher fatty aldehydes based on the calorimetric estimation of the aldehyde p-nitrophenylhydrazones formed. The derivatives formed may be isolated on a micro scale, thus facilitating the study of the metabolism of these compounds by the isotopic tracer technique.’ Presumably all of the higher fatty aldehydes measured by the present method as well as others occur in the acetal phosphatides.