Liquid Chromatographic Determination of Vitamin C in Aquatic Organisms

Abstract

A reversed-phase ion-pair liquid chromatographic method using electrochemical detection and internal standardization with isoascorbic acid (IAA) is described for the determination of ascorbic acid (AA) and dehydroascorbic acid (DHAA) in aquatic organisms. Several extractants are compared with regard to recovery and stability of AA and DHAA, including 5% metaphosphoric acid (MPA)—0.54mM ethylenediaminetetraacetic acid (EDTA), 1 % acetic acid (Hac)—1 mM EDTA, 1 % Hac—0.1 % MPA—1 mM EDTA, 2mM homocysteine—1 mM EDTA, and water—methanol (70:30, v/v) containing 0.7mM EDTA. The two nonacidic extractants afford insufficient protection of AA (water—methanol—EDTA) or DHAA (homocysteine—EDTA). High ionic strength acidic mixtures (e.g., 5% MPA) may be associated with a negative drift in the retention times of AA and IAA. Hac (1 %)—EDTA (1 mM) yields lower recovery except when supplemented with MPA. A mixture of 1 % Hac—0.1 % MPA—1 mM EDTA is useful in extracting AA from the brine shrimp Artemia, Brachionus, fish eggs, fish larvae, and postlarvae of shrimp as part of its routine high-performance liquid chromatographic determination in these matrices.