the phenanthroline assay developed by gutteridge ( biochem . j . 218 , 983-985 ; 1984 ) is shown to measure all these forms of copper down to a sensitivity of 0.1 mumol/dm3 , yet it does not detect any copper ions in freshly-prepared serum or plasma from rats , mice , rabbits or guinea-pigs , or freshly-prepared serum from humans .
C0032105
plasma
C0229671
serum