UV Photochemical Vapor Generation Sample Introduction for Determination of Ni, Fe, and Se in Biological Tissue by Isotope Dilution ICPMS

A novel, sensitive method is described for the accurate determination of Ni, Se, and Fe in biological tissues by isotope dilution inductively coupled plasma mass spectrometry (ID ICPMS) based on sample introduction arising from online UV photochemical vapor generation (UV-PVG). Volatile species of Ni, Se, and Fe were liberated from a formic acid medium following exposure to a UV source. Sensitivities were enhanced 27- to 355-fold compared to those obtained using pneumatic nebulization sample introduction. Although precision was slightly degraded (a factor of 2) with ultraviolet photochemical mediated vapor generation (UV-PVG), limits of detection (LODs) of 0.18, 1.7, and 1.0 pg g(-1) for Ni, Se, and Fe, respectively, based on an external calibration, provided 28-, 150-, and 29-fold improvements over that realized with conventional pneumatic solution nebulization. Method validation was demonstrated by determination of Ni, Se, and Fe in biological tissue certified reference materials (CRMs) TORT-2 and DORM-3. Concentrations of 2.33 +/- 0.03, 5.80 +/- 0.28, and 109 +/- 2 microg g(-1) (1SD, n = 4) and 1.31 +/- 0.04, 3.35 +/- 0.18, and 353 +/- 5 microg g(-1) (1SD, n = 4) for Ni, Se, and Fe, respectively were obtained in TORT-2 and DORM-3, in good agreement with certified values.