Selective kinetic fluorimetric determination of copper at the ng ml level

A kinetic fluorimetric method for copper, based on a previously described system with 1,1,3-tricyano-2-amino-1-propene as reagent, has been developed. It has been shown that the determination is based on copper-catalysed oxidation of the reagent rather than on complex formation with it, although complex-formation with imidazole seems needed to stabilize the copper(I) that is thought to be the catalyst. The application of several kinetic methods (tangent, fixed-time and variable-time) allows determination of very low concentrations of copper (1-35 ng ml ) with a sensitivity about 100 times that of an earlier method. Of 47 ions tested, only EDTA interfered when present at the same concentration as copper. The method has been applied to the determination of copper in blood serum samples.