検知管による水中微量水銀の迅速定量

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A rapid and simple method for the simultaneous determination of inorganic and organic mercury in water was studied. The apparatus used were a gas washing vessel (capacity 100 ml), mercury vapour detector tubes and a handy sampling pump (aspirator). Silica gel of 4060 mesh mounted with copper iodide are filled up in the mercury vapour detector tube which is 2 mm in diameter and 60mm in length. The mercury vapour is determined utilizing empirical relationships between the length of stain and its concentration. Analysis was carried out as follows : Sample water (50 ml) containing mercury compounds was placed in a gas washing vessel and reduction reagents were added. The reduced mercury vapour purged by the aeration in this vessel was led into the detector tube by sucking with a pump or an aspirator. The stained length in the tube was proportional to the amounts of mercury compounds in water. The mercury compounds differed one another in the reactivity. Both Hg(I) and Hg(II) were reduced by adding 5 ml of 18 N sulfuric acid and 5 ml of 5 N sodium chloride with tin (II) (acid method). But organic, mercury compounds were not reduced with the acid method. On the other hand, Hg(I), Hg(II), phenyl mercuric acetate, methyl mercuric chloride were reduced with tin(II) after addition of 10 ml of 10 M sodium hydroxide and traces of Cu(II) ion (alkali method). The ratio of the stained length to the amounts of mercury compounds in water by the acid method was equal to that by the alkali method. The length of a stain had a difinite value in correspondence to the amounts of mercury in water when the volume of aeration for separating mercury from water attained to 600700 ml at the average velocity 75150 ml/min. Interference of the reduction of mercury compounds with coexisting substances in alkali method was smaller than that in the acid method except when silver ions were present. When nitrous ions were present more than 10 ppm nitrogen dioxide was generated and disturbed the determination of mercury by the acid method, because nitrogen dioxide produce a stain similar to that produced by mercury (grayish yellow or pale orange). However, the stains of hydrogen sulfide (pale brown) and ammonia (light blue) which were generated from sulfide ions in the acid method and ammonium ions in the alkali method, respectively were distinguishable from that of mercury. This method was applied to the analysis of submicrogram amounts of mercury in waste waters and river waters. In the majority of cases the results approximately agreed with those obtained by atomic absorption spectrophotometoric method with wet digestion. The range of determination was 0.050.7 μg of Hg in 50 ml and the coefficient of variation was 5% at 14 ppb level. The time required for a sample was about 8 minutes.
社団法人日本分析化学会の論文

検知管による水中微量水銀の迅速定量

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