炎光分光分析法による中性洗剤,乳製品中の食塩の定量法

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Determination of inorganic chlorine in neutral detergents shown in Table I by the usual method was encountered with various difficulties. The authors established a practical method by applying the flame spectrophotometric determination of silver after converting inorganic chlorine in sample into silver ammine chloride. The sample is dissolved in hot water, acidified with nitric acid, and silver nitrate is added. After being stirred for 1 min. the precipitate is easily and quantitatively filtered at 6070°C as silver chloride (Table II). The optimal pressures of oxygen and hydrogen gases for the flame spectrophotometry are 0.8 and 0.36 atm./cm2, respectively (Figs. 1 and 2). The amount of ammonia required for the conversion of silver chloride into silver ammine chloride is over 230 times of that from the theory. It is recommended to add 10 mlNH4OH (1 : 10) for the samples containing chlorine less than 0.6mg (Table III). Silver ammine chloride gives the same calibration curve as that for silver nitrate (Fig. 3). The recovery of inorganic chlorine in the neutral detergents was above 95% (Table IV and V) with variation coefficient of ca. 8% (Table VI). The lower limit for the determination of chlorine was 0.005% and the time required for a run was 40 min.. The results on commercial neutral detergents and dairy products are shown in Table VII.
社団法人日本分析化学会の論文