ICP-MS details

ICP-MS stands for Inductively Coupled Plasma Mass Spectrometry. We have a Thermo Scientific Element 2 for quantitative analysis of trace and ultratrace elements and isotope ratios in geological and non-geological samples.

How the ICP-MS works
The sample material is introduced into the spectrometer as an aerosol by argon carrier gas (for solution) or an Ar/He mixture for laser ablation. Aerosol particles are generated either by nebulizing a sample solution or by ablating solid material with a laser. When carried through the hot plasma (up to 8000°C), the sample material is dissociated, atomized and ionized within milliseconds. The ions enter the mass spectrometer via the plasma interface, after which they are mass- and energy-filtered and the intensities at individual masses are determined.

The Element2
is a high-resolution, double focusing ICP mass spectrometer with very high sensitivity. Practical limits of detection are on the order of 1 ppt (= 1 part per trillion) for many elements and are generally better than 100 ppt. The Element2 has three resolution modes: low (resolution = 300), medium (resolution = 4,000), and high (resolution = 10,000). Medium and high resolution modes provide separation of the analyte signal from spectral interferences, making accurate and precise elemental analysis of trace element in complex matrices possible. The ion beam passes through a magnetic field generated by a large magnet. The magnetic field is dispersive with respect to ion energy and mass. The second focusing occurs at the electro-static analyzer or ESA. The ESA is dispersive with respect to ion energy and focuses the ion beam through the exit slit to the detector.

Specifications
Sensitivity: > 1 x 109 cps/ppm for In
Detection Limits: < 1 ppq (theoretical, non-interfered)
Dark Noise: < 0.2 cps
Dynamic Range: > 109 linear

Sample types
We specialize in laser ablation of solids for U-Pb geochronology and trace elements. For in-situ laser ablation ICP-MS, the sample can be any type of solid, quantification needs appropriate internal or external standardization. A 193 nm wavelength, ultra short pulse ArF Excimer laser has a sample chamber suitable for nine one-inch grain mounts or 4 standard size thin sections. U-(Th)-Pb geochronology, trace element fingerprinting, trace element thermometry are the main applications for this set-up. Short, ca. 4 ns, pulsing of the laser minimizes heating of the area around the ablation pits and produce flat-bottomed craters without melting. The 193 nm wavelength produces small particles that minimize element fractionation, and provide excellent coupling of the laser with materials of different color and transparency.

Liquid samples can be analyzed too. For solution ICP-MS, materials are dissolved with ultrapure acids and procedures. Carbonates are simply dissolved in diluted nitric acid. Silicate rocks can be decomposed by concentrated nitric acid, hydrochloric acid and hydrofluoric acid and heating at ca. 200 °C in teflon beakers or stainless steel pressure vessels. An Elemental Scientific (ESI) autosampler dedicated to the Element2 (SC-E2 with FAST) is attached directly to the ICP-MS on the nebulizer side of the instrument.

Prospective Ph.D. and M.S. research and postdoctoral researchers who wish to work on research topics in geochronology, crustal evolution, geochemistry, metamorphic petrology, please email Andreas Moeller or visit Andreas' webpage for further contact information. Requests for collaboration and analytical services are welcome from academic and industrial customers.

LABORATORY EQUIPMENT
High-resolution, double focusing magnetic sector field ICP-MS
Thermo Scientific Element 2
Photon-machines ANALYTE.G2, 193 nm ArF excimer laser ablation system
Autosampler ESI SC-E2 with FAST valve

SUPPORT EQUIPMENT:
15kWh UPS system
ThermoScientific Neslab Thermoflex 2500 chiller

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Upcoming Colloquium

SPRING 2021

2/25/21: Dr. Katherine Ryker, Assistant Professor, University of South Carolina

3/25/21: Dr. Jonathan Payne, Professor, Geological Science, Stanford University, Stanford, California.

4/8/21: Dr. Peter Burgess, Professor of Sedimentary Geology and Head of Earth Sciences, University of Liverpool, Liverpool, United Kingdom.

4/29/21: Dr. Hildegard Westphal, Professor, Geoecology & Carbonate Sedimentology and Director of the Center for Marine Environmental Science, Bremen University, Bremen, Germany.

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