Determination of Trace Copper by Fluorescence Spectrophotometry Based on Cu(DP)2+ and Cu-4.0-Generations Polyamidoamine Dendrimers Catalyze Cu2+ to Oxidize Fluorescein

摘要

Fluorescein can emit strong and stable fluorescence.Cu can oxidize fluorescein,which causes the fluorescence signal to diminish.Cu(DP)2+ (DP refers to alpha,alpha'-dipyridyl) and Cu-GPD-4.0 (GPD-4.0 refers to 4.0-generations polyamido- amine dendrimers) both can catalyze Cu2+ to oxidize fluorescein,which causes the flu- orescence signal to diminish sharply.The DELTAF is directly proportional to the content of copper.Based on the facts above,a new catalytic fluorescence spectrophotometry for the determination of trace copper using Cu(DP)2+ and Cu-GPD-4.0 was established.The linear range of this method is 0.040-28 pg mL-1.The regression equation for working curve is DELTA F = 209.5 + 14.39 C_(Cu)~(2+) (pg mL-1),n = 7;correlation coefficient is 0.991.The detection limit of this method is 1.0 x 10~(-14) g mL-1.After replicate measurement times,RSDs are 3.1% and 4.2% for samples containing 0.040 and 28 pg mL-1 Cu2+,respectively.The method is rapid and precise with high sensitivity and good repeatability.The method has been applied to the determination of trace copper in tea and human hair with satisfactory results.Meanwhile,the mechanism for the determination of trace copper by catalytic fluorescence spectrophotometry using Cu(DP)2+ and Cu-GPD-4.0 was also discussed.