Isolation of organic anions by extraction with liquid anion exchangers and its application to micromethods for acetylcholinesterase and 4-aminobutyrate aminotransferase.

Organic anions of particular importance to biochemistry such as Krebs cycle intermediates, glycolysis intermediates, simple fatty acids, adenine nucleotides and CoA derivatives can be quantitatively extracted from a buffered solution by high-molecular-weight ammonium salts in an organic solvent. Phosphate salts of tertiary amines in chloroform were the most efficient extractants. The isolation procedure was found to be an example of amine neutralization. The effect of pH, different inorganic anions, volume ratios between the two phases, concentration of the isolated anions and concentration of the ammonium salts have been investigated. The extraction technique has been applied to rapid and sensitive radiochemical methods for the determination of acetylcholinesterase and 4-aminobutyrate aminotransferase activities.