We use the following instrumentation in our laboratory:
IsoProbe Multicollector Plasma Mass Spectrometer:
This instrument uses an inductively-coupled plasma as a highly efficient ion source. Upon entering the vacuum system, the ion beam collides with gases in a hexapole collision cell; these collisions eliminate many of the common polyatomic interferences (e.g. ArO+) and reduce the energy spread of the ion beam with minimal transmission loss. The beam is shaped by an adjustable slit and is accelerated by 6000V before entering a magnetic sector mass spectrometer; the slit is imaged in a flight tube with a 15% mass range and collected by an axial Daly ion counter, two low mass/axial and seven high mass movable Faraday cups.
The forte of this instrument is high transmission (3E9 counts per second for 1 ppm U using conventional 1ml/min. Meinhard nebulizer and hard extraction). With recent expansion vacuum pump upgrade, soft extraction, and Micromist nebulizer with APEX/SPIRO desolvation, we have obtained up to 10E9 cps for 1 ppm U at 50 µl/min (i.e. ~0.3% transmission of sample atoms to detector). The high transmission allows for sensitive isotope dilution trace element analysis and the collision cell of the IsoProbe results in minimal polyatomic interferences (e.g. no ArN+ or ArO+) so we can measure nM Fe levels on 1.5 ml seawater samples. Multicollection allows for high precision isotope ratio analysis of elements such as Fe, Hf, and Pb. An axial Daly ion counting detector (recently upgraded to a new ISOTOPX design) has high stability and linearity, and near the top of its range its precision and accuracy is comparable to Faraday cups. The high abundance sensitivity achieved by the WARP filter on the Daly detector allows for measurement of trace Th-230 and U-234 for geochronological studies.
Plasmaquad 2+ Quadrupole Plasma Mass Spectrometer:
This instrument uses an inductively-coupled plasma as an ion source for sensitive multi-element analysis over a broad range of concentrations. The sensitivity of our instrument is high compared to others of the same generation (>200,000 counts per second for 1 ppb U using conventional Meinhard nebulizer) and the ability to perform rapid scan (1 millisecond per 250 amu) is ideal for elemental analysis. We use this instrument for the analysis of trace elements in seawater concentrates by isotope dilution (e.g. Pb, Cu, Cd) and for the analysis of minor elements in foraminifera (Mg, Sr).
Hitachi Z8100 Zeeman Graphite Furnace/Flame Atomic Absorption Spectrophotometer:
This instrument uses plane-polarized DC Zeeman background correction to correct for broadband ("smoke") interferences in atomic absorption spectra. It is highly sensitive for many trace elements such as Cd (absolute detection limit is ~1E-14 mole); we use this capability for the analysis of trace elements such as Cd and Mn in foraminifera.
Canberra Broad Energy Germanium Detector (BEGD):
We have recently installed a high sensitivity GeLi detector for the measurement of trace radionuclides such as Pb-210 and Cs-137.
Dionex Ion Chromatograph:
This instrument separates ions using anion or cation columns with conductivity detection after the eluent is neutralized by a suppressor column. This instrument is used for the analysis of anions such as SO4= and Cl- in natural water samples.
This page was last revised on July 18, 2012.