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微量镉的吸光光度测定无论是用双硫腙、偶氮试剂或碱性染料作显色剂,一般都要采用有机溶剂萃取。利用水相显色反应测定微量镉方法已见报道。我们的研究表明:煌绿在碘化钾存在下与某些金属离子形成的三元离子缔合物具有良好的吸光光度性质和实用价值。在pH=1～2的硫酸介质中,镉-碘化钾-煌绿形成稳定的蓝绿色溶液,而过量的显色剂由于在强酸介质中质子化使其绿色退去。反应灵敏度高,摩尔吸光系数ε_(670nm)=1.2×10~5l·mol·cm~(-1);25ml溶液中镉含量为1～15μg时符合比耳定律;且选择性较好。可用于金属、矿物及废水中微量镉的测
Absorbance spectrophotometry determination of trace amounts of cadmium either with dithizone, azo reagent or a basic dye as a developer, generally have to use organic solvent extraction. The use of aqueous color reaction determination of trace cadmium has been reported. Our study shows that: brilliant green in the presence of potassium iodide and some metal ions formed ternary ion association has good absorbance properties and practical value. In pH = 1-2 sulfuric acid media, cadmium-potassium iodide-brilliant green forms a stable blue-green solution, whereas excess developer retreats green due to protonation in a strong acid medium. The reaction sensitivity is high, molar extinction coefficient ε 670nm = 1.2 × 10-5l · mol · cm -1, Beer’s law is obeyed when the content of cadmium in 25ml solution is 1-15μg, and the selectivity is good. Can be used for determination of trace cadmium in metals, minerals and waste water