Method Description

This assay is performed on an inductively coupled plasma-mass spectrometer. Calibrating standards and blanks are diluted with an aqueous acidic diluent containing internal standard(s). Quality control specimens and patient samples are diluted in an identical manner. In turn, all diluted blanks, calibrating standards, quality control specimens and patient specimens are aspirated into a pneumatic nebulizer and the resulting aerosol directed to the hot plasma discharge by a flow of argon. In the annular plasma the aerosol is vaporized, atomized, then ionized. The ionized gases plus neutral species formed in the annular plasma space are aspirated from the plasma through an orifice into a quadrupole mass spectrometer. The mass range from 1 to 263 amu is rapidly scanned multiple times and ion counts tabulated for each mass of interest. Instrument response is defined by the linear relationship of analyte concentration vs. ion count ratio (analyte ion count/internal standard ion count). Analyte concentrations are derived by reading the ion count ratio for each mass of interest and determining the concentration from the response line.(Nixon DE, Burritt MF, Moyer TP: The determination of mercury in whole blood and urine by inductively coupled plasma mass spectrometry. Spectrochimica Acta, Part B-Atomic Spectroscopy 1999;54:1141-1153; Hanley MM, Eckdahl SJ, Kiedrowski B, et al: A comparison of methods for attenuation of oxide interferences in cadmium and mercury analysis by ICP-MS [Abstract 627]. 38th Federation of Analytical Chemistry and Spectroscopy Societies, Reno, NV, October 2-6, 2011)