P-ジメチルアミノベンザルロダニンによる金の比色定量

概要

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A colorimetric determination of gold by the use of an alcoholic solution of <I>p</I>-dimethylaminobenzal-rhodanine has been carried out, and satisfactory results were obtained. The colorimetric determinaiotn of red-colored gold-rhodanine was made by using a 100 cc of sample solution containing 5 cc of 0.003 % rhodanine solution acidified with HCl, with a 562 mμ filter and a 10mm cell. The determination was found to follow Beer's law in the range of 0.030.3 ppm of gold. In carrying out the experiment, a 100 cc of sample solution containing 5 cc of 0.003 % <I>p</I>-dimethylaminobenzalrhodanine showed the maximum light absorbancy. The change in the amount of HCl (1:20) to 38 cc had no effect on the light absorbancy. The goldrhodanine compound salt solution showed a definite light absorbancy after standing for 5 minutes and remained stable for 30 minutes thereafter. There was no effect caused by the presence of Cu below 150 mg; of Fe below 300 mg, provided that sodium metaphosphate was used ; and of Ag below 200 γ, provided that NaCl was used.