超高灵敏显色反应及其应用的研究 Ⅱ.汞(Ⅱ)-乙基罗丹明 B-碘化物体系

STUDIES ON EXTRA-HIGH SENSITIVE COLOUR REACTIONS AND THEIR APPLICATIONS Ⅱ.MERCURY-ETHYL RHODAMINE B-IODIDE SYSTEM

本文研究了在聚乙烯醇-124存在下,汞(Ⅱ)-乙基罗丹明B_碘化物超高灵敏显色体系及其反应机理。缔合物λ_(max)=605nm,表观摩尔吸光系数ε_(605nm)=1.14×10~6L.mol^(-1).cm^(-1)。汞(Ⅱ)浓度在0—2.5μg/25ml时符合比耳定律。方法可用于水样及地球化学标样中痕量汞的测定。

A highly sensitive spectrophotometric method has been developed for determination of trace mercury,based on the formation of a complicated ion-association complex of mercury (Ⅱ) with ethyl rhodamine B (ERB) and iodide in the presence of polyvinyl alcohol-124. The maximum adsorption of the ion-association complex is at 605 nm and its apparent molar absorptivity is 1.14×10~6 L·mol^(-1)·cm^(-1) at 605nm, Beer's law is obeyed for 0—2.5 μg/25ml of mercury, The interference of 18 diverse ions was studied. The molar ratio of Hg to ERB was found to be 1:4 as established by Job's method of continuous variation and the molar ratio method. The complex is supposed to be a complicated ion-association complex with the possible formula [(ERB+)_2·(HgI_4^(2-))]·12 [ERB^+·I^-]· The proposed method has been used for the determination of trace mercury in tap water, lake water and geological sample with satisfactory results. The reaction mechanism has been discussed.