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磺胺偶氮氯膦(CPA-P-SO_2NH_2)直接光度法测定土壤与铝合金中稀土元素已有报导。本文进一步研究了该显色剂在溴化十六烷基三甲基铵(CTMAB)与乙醇的存在下,与稀土元素形成多元络合物的反应条件。结果表明在0.18M盐酸-乙醇介质中,铈组稀土元素能发生灵敏度更高的络合反应,在680nm波长处表观摩尔吸光系数由εce(二元)=8.30×10~4提高到εce(多元)=1.86×10~5l·mol~(-1)·cm~(-1)。在草酸掩蔽下可用于铝合金与球墨铸铁中稀土的测定。
Direct spectrophotometric determination of rare earth elements in soil and aluminum alloy with sulfonated chlorophosphonazo (CPA-P-SO_2NH_2) has been reported. In this paper, the reaction conditions for the formation of multicomponent complexes with rare earth elements in the presence of cetyltrimethylammonium bromide (CTMAB) and ethanol were further studied. The results showed that in 0.18M hydrochloric acid - ethanol medium, the rare earth elements in the cerium group can react more sensitively, and the apparent molar absorptivity at 680nm increases from εce (binary) = 8.30 × 10 ~ 4 to εce Multivariate) = 1.86 × 10 ~ 5l · mol -1 (-1) cm -1. It can be used for the determination of rare earth in aluminum alloy and ductile iron under the masking of oxalic acid.