[Determination of trace free copper and zinc in serum samples by graphite furnace atomic absorption spectrometry after two-step precipitation of protein].

A method was developed for the determination of trace free copper and zinc in serum sample by GFAAS after two-step precipitation. The serum and ethanol were mixed with volume ratio of 1 : 2. The mixture was subsequently denatured at 70 degrees C and centrifuged to precipitate proteins. The determination, limit of copper (3sigma) was 1.2 microg x L(-1) and the recovery was 92.3% - 104%, and the determination. Limit of zinc(3sigma) was 0.098 microg x L(-1) and the recovery was 90%-107%. This two-step precipitation method can be used to determine non-protein-bound copper in tumor patients and healthy people.