Studies on the Stabilities of 5′-Ribonucleotides (IV) Analytical Applications of the Dephosphorylation of 5′-Ribonucleotides with Thorium Ion Part 2. A Simplified Determination of 5′-Ribonucleotides in their Preparations

• Published in: Food Hygiene and Safety Science (Shokuhin Eiseigaku Zasshi) Vol. 16; no. 3; pp. 160 - 164_1
• Main Authors: KUSUI, Sadao, MURAKOSHI, Akira, MORITA, Taisuke, MORI, Hideyuki
• Format: Journal Article
• Language: English
• Published: Japanese Society for Food Hygiene and Safety 05-06-1975
• ISSN: 0015-6426; 1882-1006
• DOI: 10.3358/shokueishi.16.160

A simplified procedure for the determination of 5′-ribonucleotide (5′-RNT) in seasoning preparations was developed by employing the dephosphorylation of 5′-RNT with thorium ion (Th (IV)). In the assay, 5′-RNT was catalytically dephosphorylated at pH 3 at 100°C for 120min with Th (IV) in large excess, and then determined colorimetrically on the basis of the well-known interaction between molybdate and phosphoric acid which was liberated from 5′-RNT. Before the dephosphorylation, monosodium glutamate, an inhibitor of dephosphorylation, in the preparations was removed by precipitation at its isoelectric point (pH 3.2), and the colored substances, an interfering factor in the assay of phosphate, in some preparations were also eliminated by passing through an activated charcoal column. The present method was shown to be useful for the determination of 5′-RNT in the preparations, compared with conventional enzymatic and colorimetric methods using several commercial seasoning preparations.