The microdetermination of copper in plasma protein fractions

Electrophoresis on cellulose acetate membranes and electrothermal atomization for atomic absorption spectrophotometry have been combined to allow the determination of copper in protein fractions separated from only 2 mul volumes of serum. The sensitivity of the method is 5.2 X 10(-11) g of copper for 1% absorption at 324.7 nm, and the precision of replicate analyses at the 1.7-ng level is 0.086 (Relative Standard deviation). The mean recovery of copper from the alpha2-protein fraction of a serum sample was 94%. The method has been applied to a study of the changes in the copper content of the various protein fractions of sera from patients with Menkes' syndrome.