魚肉アンモニアの比色定量法-III

Abstract

Som experiments were carried out to make quicker and easier the method for measuring ammonia in fish meat, which was reported previously by one of us. As a result, the following was found out:- 1) The instrument, which was specially devised by us to simplify the process of weighing the fish meat, proved very suitable for the present purpose. 2) Some precautions on the preparation and use of the reagents for the determination were shown. 3) By shaking vigorously with water for about one minute, ammonia was completely extracted from fish meat. 4) Mixture of potassium bichromate and cobaltous nitrate was suitable as a standard color solution for the visual measurement of color intensity in Nessler's method. Analytical procedure, thus, was led as below:- Five grams of finely minced fish meat was taken with the above described instrument and extracted with 10 volumes of water by vigorous shaking by hand for about one minute and filtered through a gauze or a cotton cloth. To 10cc. of the extract was added 2.5cc. of 15% sulphosalicylic acid containing 5% of sulphuric acid and 1.5g. of active carbon, and then it was filtered after being adequately mixed up. To 1.0cc. of the filtrate taken in the colorimetric tube was added 4.8cc. of the mixture of 1.2% sodium hydroxide with 4.2% Rochelle salt (1:1) and further to the mixed solution was added 0.2cc. of Nessler's reagent. Color-intensity was immediately compared with the standard color solution.