Spectrophotometric determination of micro-cadmium in water after ionic liquid extraction
离子液体萃取光度法测定水中微量镉

A new extraction spectrophotometry for the determination of micro-cadmium was proposed.In Na2B4O7-NaOH buffer medium at pH 10.8,the Cd-Cadion complex formed by 1-(4-nitrobenzophenone)-3-(4-phenylazophenyl)-triazene(Cadion) and Cd2+ could be extracted by little ionic liquid(1-butyl-3-methylimidazole hexafluorophosphate,).After centrifugal separation,the content of cadmium in ionic liquid phase was directly determined by spectrophotometry at maximum absorption wavelength(517 nm).The linear range of this method was 1.0-62.5 ng/mL,the detection limit was 0.22 ng/mL,apparent molar absorptivity was 6.9×105 L·mol-1·cm-1,the enhancement factor was 29.5,and the relative standard deviation(RSD,50 ng/mL,n=6) was 2.1 %.The proposed method was directly applied to the determination of micro-cadmium in water sample with recoveries of 96.7 %-108.5 %.