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文献[1、2]曾报道了β-CD对显色体系的影响,但有机溶剂对于β-CD存在显色体系的影响至今未见报道。本文研究了乙醇存在下,锌与5-Br-PADAP-β-CD的显色反应。实验表明,乙醇对此显色反应有明显的增敏作用。形成络合物的适宜pH范围为7.5—10.5,络合物的最大吸收波长为552nm,表现摩尔吸光系数为1.35×10~5L·mol~(-1)·cm~(-2),较无乙醇存在的三元体系灵敏度增大了1.6倍。锌在0-16μg/25ml范围内服从比尔定律。显色体系在四小时内保持稳定。用该法测定了水样中微量锌,得到令人满意的结果。
The effect of β-CD on colorimetric system has been reported in literatures [1,2], but the influence of organic solvents on the existence of chromogenic system of β-CD has not been reported so far. In this paper, the color reaction of zinc with 5-Br-PADAP-β-CD in the presence of ethanol was studied. Experiments show that ethanol has significant sensitizing effect on this color reaction. The suitable pH range for the formation of the complex was 7.5-10.5. The maximum absorption wavelength of the complex was 552 nm. The molar absorption coefficient was 1.35 × 10-5L · mol -1 cm -2, The presence of ethanol ternary system increased the sensitivity of 1.6 times. Beer’s law is obeyed for zinc in the range of 0-16 μg / 25 ml. Color system remained stable in four hours. This method was used to determine trace amounts of zinc in water samples, and satisfactory results were obtained.