β-环糊精交联聚合物树脂相分光光度法测定钢中镍

Determination of nickel in steel by resin phase spectrophotometry with β-cyclodextrin cross-linked polymer

以环氧氯丙烷为交联剂，合成了环糊精聚合树脂。将镍与2-（5-溴-2-吡啶偶氮）-5-二乙氨基苯酚形成的有色络合物富集在环糊精聚合树脂上，制作成薄层，利用树脂相光度法对痕量镍进行测定。确定了最佳测定条件，并对干扰离子及其消除进行了讨论。络合物的最大吸收波长为556nm，表观摩尔吸光系数为1．75×10^5L·mol^-1·cm^-1。25mL溶液中镍含量在0．06～12μg范围内服从比尔定律，方法检出限为1．5μg／L。测定镍的线性回归方程为A=0．2137C＋0．0254，相关系数r=0．9994。方法用于钢样中镍的测定，相对标准偏差小于2．0％，结果与认定值相符合。

β-cyclodextrin polymer was synthesized using epichlorohydrin as the cross-link agent. A colored complex of Ni^2＋ and 2-（5-bromo-2-pyridylazo）-5-diethylamino-phenol was enriched on the β-cy- clodextrin polymer to give a resin thin layer. The concentration of trace nickel in the resin thin layer was directly determined by spectrophotometry. The influence of coexisting ions on the reaction was discussed and the optimal conditions were investigated. Results showed the maximum absorbance of the complex was at 556 nm with the apparent molar absorptivity of 1.75）×10^5 L·mol^-1·cm^-1. The detection limit was 1.5 μg/L. Beer＇s law was obeyed in the range of 0.06--12 μg in 25 mL of solution. The regression equation of calibration was found as A = 0. 213 7C ＋ 0.025 4, with correlation coefficient of 0. 999 4 . The proposed method has been applied in the determination of trace nickel in steel,with the RSD （n=6） of less than 2.0% ,and the results are agreement with the certified values.