Catalytic Spectrophotometric Determination of Trace Cerium with Malachite Green in Water

Sensitive catalytic action of trace Ce(Ⅳ) on discoloring reaction of malachite green oxidized by potassium iodate(KIO3) in HAc-NaAc buffer solutionwasstudied.The best conditionsof the catalyticreactionwere selected and a newcatalyticspectrophotometric method for determining trace Ce(Ⅳ) was developedbased on this.The maximum absorptionwavelengthof the reagent and discoloring system in HAc-NaAc buffer solution with a pH of 5.0 are all at 620nm,and theapparent molar absorptivityis 1.1×105L·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%.