著者

渡邊 惺子 大竹 三郎

出版者

湘南工科大学

雑誌

相模工業大学紀要 (ISSN:02860910)

巻号頁・発行日

vol.3, no.1, pp.9-16, 1969-03-31

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By examining the variation of absorption by barium-sulfonazo III chelate in the presence of sodium salt, the optimum conditions in absorptiometric determination of barium with sulfonazo III have been investigated. The sulfonazo III, having two absorption maxima at 570mμ and 630mμ, makes a chelate compound with barium ion by the ratio 1 : 1 (absorption maxima : 590mμ, 640mμ). The absorvance at 640mμ, which changes itself markedly in proportion to the concentration of barium ion, may be diminished remarkably in the presence of sodium salt. The absorbancy, in this case, does not depend on the pH value, within the range of pH 1 to 10,but only depends on the concentration of sodium ion. And when barium ion is absent, sodium-sulfonazo III which has its absorption maximum at 635mμ, changes its absorbancy slightly proportionaly to the concentration of sodium ion. Such being the case, the caribration curve of barium, when a buffer solution containing sodium salt is added, has been found to be linear in wide range (&acd;3×10^<-4>M[Ba^2+]), so far as the concentration of sodium ion is high, but it has been observed to be curved in the region of [Ba^<2+>] over 1.5×10^<-5>M, when [Na^+] is 10^<-3>M (pH 4.7). In conclusion, it has been found that use of a buffer solution (pH 2.2) by monochloroacetic acid series and the concentration of sodium ion are to be adjusted between 0.02M to 0.1M, as the condition of quantitative detection of barium ion below 3.5×10^<-5>M at 640mμ.