EXAMINATION OF THE CONVENTIONAL METHOD AND A PROPOSAL FOR A NEW METHOD OF DETERMINING INOSITOL PHOSPHATE IN THE HUMIC ACID FRACTION

概要

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In order to obtain reliable values for the inositol phosphate(IP) in the humic acid fraction (HA), modification of the determination procedure was examined. Almost no IP was determined in HA by the conventional method. It was considered that problems existed in the procedures of hydrolysis with NaOH and oxidation with NaOBr, resulting in low yields of IP_6 compared to those estimated from the amount of inositol. A new method involving hydrolysis with 1 N NaOH at 100℃ for 3 hr and oxidation with 3% NaOBr at 0-5℃ for 18 hr, and leaving the material in 60℃ water for 4 hr, was able to demonstrate considerable amounts of IP in HA. The maximum value determined was 70% of the total amount of IP calculated on the basis of the amount of inositol, which might represent the maximum under the chemical treatments employed since release of inorganic phosphate from IP inevitably occurs during these procedures. Further experiments to check various problems in the procedures of IP determination indicated that the newly proposed method was reliable.