Multiple desolvatlon steps at -80 °C for a continuous-flow ultrasonic nebulizer reduced the load of water and HCI on an argon inductively coupled plasma (ICP). Consequently, the oxide ratios MO+/M+ for Ca, Mo, and La were 0.02-0.05%.Polyatomic Ion Interferences from ArO+, CIO+, and ArCI+ were also reduced by several orders of magnitude. Measured Isotope ratios for Nl, Cd, and Fe were In good agreement with accepted natural values, and the detection limits were 2-20 ng L'1 for Nl, Fe, V, As, and Cd In the presence of concentrated matrices of HCI, Ca, or Mo that would normally cause polyatomic Ion Interference. Eight additional seconds were necessary for sample rinse-out, and analyte sensitivity was reduced by a factor of 2 when cryogenic desolvatlon was used. UO+/U+ ratios were reduced to 0.06% when cryogenic desolvatlon was used and acetylene was added to the central channel. Sodium matrices up to 100 mg L1 decreased the La+ count rate but did not affect the oxide ratio LaO+/La+. At 1000 mg L~1 NaCI the LaO+/La+ ratio Increased to 0.08%.
Addition of a small dose (2%) of H2 to the aerosol gas flow enhanced analyte signals by a factor of 2-3, which compensated for the loss of analyte signal that accompanied earlier efforts at cryogenic desolvation with inductively coupled plasma mass spectrometry (ICP-MS). Vanadium, nickel, and arsenic at microgram per liter levels in urine, river, and seawater reference materials were determined. The polyatomic ions ClO+, CaO+, and ArCl+, which normally cause severe overlap interferences for these elements, were attenuated to manageable levels by cryogenic desolvation. The samples were simply diluted with 1% HNO3 so that the chloride could be removed as HCl. The analytical results obtained for these standard reference materials agreed closely with the certified or recommended values. The detection limit ranges (3 sigma) obtained were 10-1000 ng L-1 for V, 0.03-20 micrograms L-1 for Ni, and 4-7000 ng L-1 for As in the original samples. The samples were introduced by flow injection to minimize clogging of the sampling orifice.
INTRODUCTION 11 EXPERIMENTAL SECTION Instrumentation Desolvation Procedures Data Acquisition Standard Solutions RESULTS AND DISCUSSION 19 Desolvation and Plasma Characteristics 19 Background Mass Spectra and Removal of C10+, ArCl+, and ArO+ REMOVAL OF METAL OXIDES
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.