接触反応を利用する微量硫化物イオンの吸光光度定量

概要

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Although iodine does not react with sodium azide, the following reaction is catalytically promoted in the presence of micro amounts of sulfur compounds. 2 NaN_3+i_2→ 2 Nal+3 N_2 This catalytic reaction is applied to the photometric determination of a trace amount of sulfide ion. The sample solution (10.0 ml) is placed in a 15 ml glass centrifuge tube containing a precipitate of basic zinc carbonate formed by mixing 0.50 ml of zinc nitrate solution {3 g Zn(NO_3)_2・6H_2O/100 ml} with 0.50 ml of sodium carbonate solution (1.5 g Na_2CO_3/100 ml) and 0.50 ml of formaldehyde solution (37 %). After shaking, the precipitate containing zinc sulfide is separated by centrifugation. Then 5.0 ml of water is added to the precipitate, and the content is shaken vigorously. Three milliliters of the sodium azide solution (20 g/100 ml) and 2.0 ml of the triiodide solution, which is prepared by mixing a mixed reagent solution (T×10^<-3>N in KIO_3 and 1 N in KI) with an equal volume of 1 N acetic acid, are added into the centrifuge tube. The absorbance is measured at 350 nm against water at 5 min after the addition of the triiodide solution. By this method, sulfide ion in the concentration range of (2〜25)ppb can be determined. An interference of sulfite ion is removed by the addition of formaldehyde solution.
社団法人日本分析化学会の論文
1980-04-05