新显色剂4-(2-吡啶偶氮)-邻苯二酚吸光光度法测定微量Cd(Ⅱ)

Study on the Spectrophotometric Determination of Trace Cadmium with A New Chromogenic Reagent 4-(2-Pyridylazo)-Pyocatechol

研究了新显色剂4-(2-吡啶偶氮)-邻苯二酚(PAPC)与Cd(Ⅱ)的显色反应。在有机溶剂DMF及pH=10.08Na_4B_4O_7-NaOH缓冲溶液中,试剂与Cd(Ⅱ)反应生成稳定的橙色配合物,其最大吸收波长为498nm,表观摩尔吸光系数为4.9×10~5L·mol^(-1)·cm^(-1),镉含量在0～3.5×10^(-6)mol·L^(-1)范围内服从比耳定律,该方法应用于长江水与自来水中微量镉的测定,结果令人满意。

The chromogenic reaction of the new reagent 4 - (2 - pyridylazo) - pyrocatechol(PAPC) with Cadmium is studied in this paper. In the presence of N,N' - Dimethylformamide(DMF) and pH = 10.08 Na2B4O7 - NaOH buffer medium, the reagent reacts with Cd(Ⅱ) to form a stable, orange complex, which has an absorption maximum at 498 nm, with an apparent molar absorptivity of 4.9×10~5L·mol-1·cm-1, Beer's law is obeyed in the range 0 -3.5×10^(-6)mol·L-1' solution. The proposed method has been successfully applied to the determination of Cd(Ⅱ) in water with satisfactory results.