Chromatographic determination of the acids of the citric acid cycle in tissues.

Many methods are to be found in the literature for the determination of several of the individual acids of the “citric acid cycle;” however, to date no method has been available for the simultaneous determination of all of the acids in a single sample of tissue. Isherwood (1) employed partition chromatography on silica gel to separate and determine subsequently a group of acids present in fruit, some of which are members of the tricarboxylic acid cycle. This work suggested to Marshall, Orten, and Smith (2) the possible applicability of partition chromatography to the determination of the acids present in animal tissues. These workers succeeded in separating and quantitatively determining fumaric acid in muscle, liver, kidney, brain, and blood by this procedure (2) ; during this investigation, several other acids of the citric acid cycle were located on the chromatogram (3). More recently, Marshall et al. (4-6) have also determined ar-ketoglutaric, aconitic, malic, lactic, and succinic acids by the same procedure. Partition chromatography has also been employed by Marvel and Rands (7) for the determination of the chemical constitution of organic polymers. In the present study, the work of Marshall and coworkers was extended and a method for the simultaneous determination of fumaric, ac-ketoglutaric, oxalacetic, succinic, lactic, pyruvic, malic, cis-aconitic, isocitric, and citric acids was developed.