Method validation for a multi-element panel in serum by inductively coupled plasma mass spectrometry (ICP-MS)

Background: Laboratory testing for trace and toxic elements is important to diagnose metal toxicity and nutritional deficiency. There are several essential elements that are necessary for biological function and non-essential elements that can pose risk from exposure. Both essential and nonessential elements can be toxic if concentrations exceed a certain threshold. Methods: An aliquot of serum was diluted in a diluent solution, which contained iridium (Ir) as the internal standard, gold (Au), 0.05% Triton X-100, and 1% nitric acid (HNO3). The diluted specimen was aspirated into an inductively coupled plasma-mass spectrometer for quantitative elemental analysis of chromium (Cr), cobalt (Co), copper (Cu), manganese (Mn), nickel (Ni), selenium (Se) and zinc (Zn). The sample was introduced into the instrument spray chamber to form aerosol droplets, then atomized and ionized in argon plasma. The ions exited the plasma, passed through the interface of the instrument, then arrived at the entrance of the collision cell where helium gas was introduced to remove polyatomic interferences by kinetic energy discrimination (KED). After exiting the collision cell, the ions were filtered by a quadrupole mass spectrometer. Results: The analytical measurement range was determined specifically for each element. Imprecision was < 20% CV for the lowest limit of quantification for each element and accuracy was within +/- 15%. Conclusions: This method was validated for the quantification of seven elements in serum to assess nutritional deficiency and toxicity. The multi-element panel by ICP-MS met the validation criteria for biological monitoring of trace and toxic elements in patient specimens.