Reduction of polyatomic ion interferences in inductively coupled plasma mass spectrometry with cryogenic desolvation

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:6981284

Alves, L C

A new desolvation scheme for the introduction of aqueous and organic samples into an argon inductively coupled plasma (ICP) is described. The aerosol generated by the nebulizer is heated (+140[degrees]C) and cooled ([minus]80[degrees]C) repeatedly. The dried aerosol is then injected into an inductively coupled plasma mass spectrometer (ICP-MS). The metal oxide count rate ratios (MO[sup +]/M[sup +]) were drastically reduced to [<=] 0.05% for all the elements tested with the exception of the UO[sup +]/U[sup +] ratio which was reduced to 0.1%. However, the addition of acetylene to the aerosol gas flow caused only a slight increase in the analyte sensitivity ([approximately]20%) while the addition of H[sub 2] increased the analyte sensitivity five fold. Moreover, the cryogenic loops also trapped Cl[sup [minus]] species as HCl, which made possible the determination of V and As in samples containing a concentrated salt matrix. This multiple cryogenic desolvation system was validated with the analysis of seawater and urine reference samples. No sample preparation was necessary, except for dilution with 1% HNO[sub 3] to bring the total dissolved solids concentration below 0.1%. Accurate isotope ratios were also obtained for Fe, Ni, and Cd in the presence of Ca and Mo, which generally cause interferences. Samples dissolved in organic solvents are particularly troublesome for ICP-MS; the plasma becomes unstable and carbon deposits on the interface. Cryogenic desolvation was applied with methanol, ethanol, acetone, and acetonitrile. The plasma was stable with all the solvents at the same operating conditions as for aqueous samples. Some C[sub 2] emission and carbon deposition were observed when acetone and ethanol were nebulized. No green C[sub 2] band emission was observed in the plasma and only minor carbon deposition was observed on the sampling cone when methanol an acetonitrile were used.

• Research Organization: Iowa State Univ. of Science and Technology, Ames, IA (United States)
• OSTI ID: 6981284
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400102* -- Chemical &amp; Spectral Procedures
ACTINIDE COMPOUNDS
ALKALINE EARTH METALS
CADMIUM
CALCIUM
CHALCOGENIDES
ELEMENTS
ICP MASS SPECTROSCOPY
INTERFERENCE
INTERFERING ELEMENTS
IRON
MASS SPECTROSCOPY
METALS
MOLYBDENUM
NICKEL
OXIDES
OXYGEN COMPOUNDS
REMOVAL
SPECTROSCOPY
TRANSITION ELEMENTS
URANIUM COMPOUNDS
URANIUM OXIDES
VANADIUM