Analysis of copper in brain by the mass-spectrometric integrated-ioncurrent procedure

Through use of the high-resolution double-focusing mass spectrometer, copper has been identified in various regions of the mouse, rat, guinea pig, rabbit, and human brain. The procedure depends on converting the copper (in ashed tissue) to its chloride salt, followed by derivatization with tetraphenylporphyrin (TPP) to yield a TPP chelate. After chromatographic separation, this chelate is assessed in the mass spectrometer by the integrated-ion-current procedure. Deuterated metal TPP chelates and the rare stable isotope(65)Cu were used as internal standards. Whole brain values obtained were as follows: mouse, 6.67±0.16 (mean±SEM) μg/g wet weight of tissue; rat, 1.06±0.05; guinea pig, 5.40±0.63; and rabbit, 7.52±0.76. In the rat, the cerebellum contained the highest concentration (1.25 μg/g), and the striatum the lowest (0.70 μg/g). In the human brain, the cortex (gray) and the striatum were relatively the highest copper-containing regions, with the cerebellum (white) being the lowest.