Chemiluminescence investigation of NH(2)OH-fluorescein-Cu(2+) system and its application to copper analysis in serum

A novel chemiluminescent system, fluorescein-NH(2)OHOH(-), was developed for the determination of copper(II) in serum. A weak light emission arises from hydroxylamine in the presence of the organic reagent fluorescein in basic aqueous solution. Under the conditions of 1.2 x 10(-3) mol l(-1) NH(2)OH and 5 x 10(-3) mol l(-3) fluorescein, the light intensity is linearly dependent upon the concentration of copper(II) within the range 1-20 ppb. The relative standard deviation of the determination of copper(II) is 4.2% (n = 13) and the detection limit is 0.5 ppb. The system is highly selective for copper except in the presence of iron(II,III) and cobalt(II). In conjunction with potassium fluoride as masking agent, the method was successfully applied to the determination of microamounts of copper(II) in serum. A mechanistic study of the chemiluminescence reaction is also discussed.