BIOCHEMICAL STUDIES ON L-ASCORBIC ACID IN AQUATIC ANIMALS-I

AN IMPROVED METHOD FOR ASSESSMENT

Abstract

For assessment of L-ascorbic acid in fish, a hydrazine method based on the formation of 2, 4-dinitrophenyl-osazone is now in use. Under the condition prescribed for this method, however, it was found that substances contained in extracts from fish tissues would form interfering osazones and thus affect assessment of ascorbic acid (Table 2).
Analysis revealed that major components of these impurities consisted of amino acids, and the rest were sugars and organic acids. Among the amino acids, histidine had the largest influence upon the osazone formation; tyrosine and tryptophan also affected the result of assessment (Table 3 and Fig. 2). Some of sugars and organic acids affected the assessment only when they were present at a relatively high concentration in the test solution. They were glucuronic acid, glucuronolactone, galacturonic acid, oxaloacetic acid, and pyruvic acid (Table 4).
As chromatography through an acid alumina column could thoroughly separate the interfering osazones, the use of the chromatographic treatment is proposed in order to improve the ascorbic acid assessment by the hydrazine method (Fig. 4).