Isotope ratios provide important opportunities for understanding the physical and chemical processes that shape the modern Earth system and that have controlled the evolution of the Earth over its 4.55 billion year history. These measurements are made primarily on the Thermo Neptune (a multi-collector, sector field, plasma-source mass spectrometer). 

Using this instrumentation, researchers at CEMS now routinely measure isotope ratios for a diverse suite of elements, including Si, B, Fe, Zn, Cd, Sr, Nd, Hf and Pb.  These data are used to understand a wide variety of processes, including those controlling the composition of modern seawater, and those that shaped the formation of the earliest continental crust.   

The high-resolution, Element II and Varian 820-MS quadrupole mass spectrometers are used primarily for trace metal abundance measurements in solutions at ppt and sub-ppt levels.  These instruments are capable of measuring trace abundances in any sample that can be dissolved in a dilute acid solution, for most elements in the periodic table.  

Quantitative measurements of samples using these instruments are typically made by running them against matrix-matched analytical standards, or by more precise methods such as standard addition or isotope dilution.

The Photon Machines Eximer 193 nm laser system allows us to make direct, in-situ and non-destructive measurements on solid samples at high spatial resolutions (< 10 micron).  The laser system, which is most often coupled to the Element II high resolution ICP mass spectrometer, may be used for making both trace metal abundance and isotope ratio measurements.  

The CEMS laser is used most-often to measure isotope ratios for U and Pb in zircon samples collected from a wide range of rock types.  Zircon ages calculated from these data play a key role in understanding a wide variety of geologic systems. 

The CEMS clean lab is a 600 square-foot, metal-free laboratory, designed for open counter, low-blank sample handling.  Air is supplied by a ceiling-mounted HEPA filtration system that operates at one air exchange per minute.  Sample heating and drying is done in custom-made HEPA filtered dry-down stations that are rated for perchloric acid.  Several sub-boiling acid distillation units provide ultra-clean acids (HF, HNO3, HCl) for low-blank sample dissolution and column chemistry.  

The lab includes a recirculating 18 MOhm water system fed by a reverse osmosis system coupled to a Millipore Super-Q.  Other ancillary equipment  include microbalances, centrifuges, and sonic baths.

Solution ICPMS: The Thermo High Resolution ICPMS ELEMENT2 permits the analysis of elements that suffer from polyatomic interferences (e.g. 40Ar35Cl on 75As, or 40Ar16O on 56Fe).   By physically separating the ion of interest from the interfering polyatomic species it enables more accurate and precise data, thus eliminating additional sample preparation that is often required for some elements.  Moreover, the high sensitivity of the system allows the analysis of a wide range of matrices.  Standardization is done with a combination of internal standards (typically indium) and external calibration by well-characterized USGS rock standards and multi-element solutions.  Analysis by standard addition or isotope dilution can also be performed for an additional cost, as these types of analyses are more labor intensive and require additional instrument time.  A typical element suite contains the following elements:  Rb, Sr, Y, Zr, Nb, Cd, Sn, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, Pb, Th, U, Li, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Ga.  Additional elements or different combinations of elements can be analyzed based on the customers needs.  There is no additional cost for more or fewer elements.

The 193 nm Photon Laser system coupled to the Thermo ELEMENT2 provides in situ concentration analyses of minerals and other solid compounds without the need for chemical separations.  The spatial resolution is 10 microns, depending on concentration.  CEMS routinely analyzes silicate minerals for concentration, zircons for U-Pb dating, and sulfides for platinum group elements and other siderophile and chalcophyle elements.  We can also provide spatially resolved elemental concentration maps of entire areas of the analyzed sample if the spatial distribution of an element is needed.  Concentrations are typically calculated using NIST and USGS standards.  

The Thermo Neptune PLUS coupled with the ESI APEX introduction system allows for very high sensitivity, around 1,500 V / ppm for Nd, Hf and Pb.  Depending on concentrations, different introduction systems are used to optimize the acquired data. The isotope ratios are run against well-characterized international reference materials.