在HAc-NaAc缓冲介质中,痕量铈(Ⅳ)可灵敏地催化 KIO_3 氧化孔雀石绿的褪色反应,据此研究了该反应的最佳条件,建立了催化光度法测定痕量铈的新方法.结果表明,在pH=5.0的HAc -NaAc缓冲介质中,试剂及褪色体系的最大吸收波长均为620nm,表观摩尔吸光系数为ε=1.1×10~5L·mol~(-1)·cm~(-1),铈(Ⅳ)量在0～0.4μg·mL~(-1)范围内与孔雀石绿的褪色程度呈良好的线性关系,其线性回归方程为△A=0.0285c(μg/25mL)+0.0036,相关系数r=0.9994,检出限为 8.8ng·mL~(-1).该法可直接用于自来水中痕量铈的测定,加标回收率为94.0%～99.0%,结果满意.
Sensitive catalytic action of trace Ce(Ⅳ) on discoloring reaction of malachite green oxidized by potassium iodate (KIO_3) in HAc-NaAc buffer solution was studied. The best conditions of the catalytic reaction were selected and a new catalytic spectrophotometric method for determining trace Ce(Ⅳ) was developed based on this. The maximum absorption wavelength of the reagent and discoloring system in HAc-NaAc buffer solution with a pH of 5.0 are all at 620nm,and the apparent molar absorptivity is 1.1×10~5L·mol~(-1)·cm~(-1). The linear range is 0μg～0.4μg·mL~(-1) for Ce (Ⅳ),the corresponding linear regression equation is △A = 0.0285c(μg/25mL)+0.0036,and the correlation coefficient is 0.9994. The detection limit is 8.8 ng·mL~(-1). The method was applied to the direct determination of trace Ce(Ⅳ) in water sample with satisfactory results,and the method recovery were 94.0%～99.0%.
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