キシリジルブルー法による微量マグネシウムの比色定量
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概要
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A method for the determination of traces of magnesium has been devised, based on the formation of a colored complex of magnesium with xylidyl blue reagent, sodium 1-azo-2-hydroxy-3-(2, 4-dimethylcarboxanilido)-naphthalene-1'- (2-hyd-roxybenzene-5-sulfonate). When solutions are kept at pH 9.0 with 0.08 <I>M</I> borax buffer, and then prepared with 95% ethyl alcohol, the absorption spectrum of the reagent shows an absor-bancy maximum at 615 mμ that of the complex shows maxima at 510 and 540 mμ. Magnesium may be calculated from the absorbancy at 510 mμ and at 615 mμ. For the purpose of determining traces of magnesium in sea water and brine from which magnesium was removed, the effects of the presence of sodium, calcium, and influence of water in this method were studied. The presence of sodium gave a positive error and that of calcium gave a negative error. But because the magnitude of each error is limited, this error due to sodium or calcium could be corrected by the addition of more than 400 ppm of sodium or more than 5 ppm of calcium. When sodium and calcium coexisted, the effect of both ions could be compensated for by thus preparing the solution properly. The concentration of ethyl alcohol had to be maintained at more than 80%. The accuracy and the precision of this method were good; the precision expressed as a standard deviation from the mean was 3.9% of the magnesium present. The absorbancy-concentration curve was linear up to 0.4 ppm.
- 社団法人 日本分析化学会の論文