Simultaneous determination of coinage metals, copper, silver, and gold in tissues using electrospray ionization tandem mass spectrometry

A rapid and sensitive mass spectrometric method was developed for the simultaneous determination of the coinage metals of copper (Cu), silver (Ag), and gold (Au). The metals in a wet-ashed tissue solution were complexed with diethyldithiocarbamate (DDC; C4H10NCS2) and were extracted with isoamyl alcohol. After acidification of the extract with oxalic acid, metals were quantified using their product ions, Cu(DDCH)+, Ag(DDCH)+, and Au(DDCH)+ that derived from the precursor ions Cu(DDC) 2 + , Ag(DDC) 2 + , and Au(DDC) 2 + , respectively, by electrospray ionization tandem mass spectrometry. The limits of detection were 0.6, 0.3, and 1 μg/l for Cu, Ag, and Au, and the quantification ranges were 2–100, 1–100, and 3–100 μg/l for Cu, Ag, and Au, respectively. Cu levels in spontaneously hypertensive osteogenic disorder rats at 6 weeks of age and 30 weeks of age were found to be 1.8 times and 5.1 times those of the normotensive osteogenic disorder rats, respectively, when using wet-ashed kidney solutions diluted 1000-fold.