Abstract
A simplified colorimetry procedure was developed for the determination of sodium 5′-inosinate (5′-IMP) in sodium 5′-ribonucleotide (5′-Rb) and in flavor-enhancing preparations consisting of monosodium L-glutamate (92-98.5%) and 5′-Rb (8-1.5%).
In the present method, 5′-IMP was decomposed to diazotizable amine (DA) by treatment with zinc powder in dilute hydrochloric acid. The DA formed a reddish-purple-colored derivative with the Bratton-Marshall reagent, with an absorption maximum at 540nm. A linear relationship was observed between absorbance at 540nm and concentration of 5′-IMP in the range of 5-50μg/ml.
Interfering substances in the present method were similar to those in the official method for the determination of 5′-IMP in 5′-Rb or in flavor-enhancing preparations.
The time required for assay by the present method was reduced to about one-third of that required by the official method.
