Determination of glutamine, glutamic acid and pyroglutamic acids using high-performance liquid chromatography on dynamically modified silica

Abstract

For the determination of glutamine and the products of its degradation, glutamic and pyroglutamic acids, in fermentation broth and other biotechnological samples, a rapid and convenient high-performance liquid chromatographic method is proposed. The method is based on the separation of these compounds on silica dynamically modified with Cu(II) ions. Modification is obtained by the addition of copper sulphate to the mobile phase. The copper complexes of amino acids, including pyroglutamic acid, are easily formed in the column and are detected by UV absorption at 235 nm. If it is necessary to improve the separation, an ion-pairing reagent (sodium dodecyl sulphate) is added to the mobile phase. Using this method, the levels of glutamine and related compounds are determined in fermentation media of industrial strains and other biotechnological samples. The total time of analysis is less then 10 min with a detection limit of 0.1 g/l.