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利用四(对羟基苯基)卟啉(TOPPH_2)为显色剂,在β-环糊精作用下,研究了TOPPH_2与Pb~(2+)的显色反应。结果显示,在pH 10.0,沸水浴加热15 min,Pb~(2+)与TOPPH_2形成稳定的配合物TOPPPb(Ⅱ),在λ_(max)=436 nm检测吸光度,发现该条件下显色剂吸收峰较宽。当显色液冷却至室温,加入一定量β-环糊精,震荡20 min,调节pH为4.6,发现溶液在426 nm处有较窄的吸收峰,显色反应得到增强,当Pb(NO_3)_2质量浓度范围为0~0.15 mg/L,吸收峰强度与溶液中Pb~(2+)的浓度成正比,符合比尔定律。
The color reaction of TOPPH_2 with Pb 2+ was studied by using β-cyclodextrin with tetrakis (p-hydroxyphenyl) porphyrin (TOPPH 2) as chromogenic reagent. The results showed that PbPP (Ⅱ) formed a stable complex with TOPPH_2 at pH 10.0 for 15 min in boiling water bath, and the absorbance was measured at λ max = 436 nm. It was found that under these conditions, The peak is wider. When the chromogenic solution was cooled to room temperature, a certain amount of β-cyclodextrin was added and shaken for 20 min to adjust the pH to 4.6. It was found that the solution had a narrower absorption peak at 426 nm and the chromogenic reaction was enhanced. When Pb (NO 3) _2 mass concentration range of 0 ~ 0.15 mg / L, the absorption peak intensity is proportional to the concentration of Pb ~ (2+) in solution, in line with Beer’s law.