Disassociation of glutamate from γ-aminobutyric acid by zinc acetate-assisted differential precipitation/dissolution: Application to the quantification of γ-aminobutyric acid

Abstract γ-aminobutyric acid (GABA) is a key physiologically active molecule in organisms. Separation of glutamate from its decarboxylated product GABA has been vigorously pursued. The interaction between these two compounds severely hindered their disassociation. Herein, we present a new strategy, termed zinc acetate-assisted differential precipitation/dissolution (ZA-DPD), for the removal of glutamate by step by step recovering pure GABA solution and discarding pure glutamate pellet, essentially attributed to the use of two core reagents (zinc acetate-assisted glutamate-precipitating reagent, and glutamate-rejecting reagent). In each precipitation, the zinc acetate-assisted glutamate-precipitating reagent guaranteed most GABA still soluble although the rest co-precipitated with glutamate; in the coupled dissolution, the co-precipitated GABA was fully dissolved with or without (in the case of glutamate-rejecting reagent used in the final dissolution) co-dissolution of glutamate. The process was repeated twice until glutamate was thoroughly removed. An accurate quantitative method coupling ZA-DPD with colorimetry was thereafter established for the determination of GABA. This study may facilitate the areas associated with GABA or glutamate.