Isotope Geochemistry

Devlin Hall laboratory houses a 750 sq. ft. Class 1000 trace-metal clean room constructed to minimize contamination during ultra-trace level chemical processing. These metal-free, HEPA-filtered laboratories are specifically designed for handling sub-nanogram sample quantities. The clean rooms feature 14 Class 100 ULPA-filtered laminar flow benches and hoods, Savillex Teflon distillation units, Analab metal-free hotplates, and precision analytical balances. Environmental control is maintained through consistent temperature regulation and monitored positive pressure, with a Setra Multisense system providing real-time feedback at each lab entrance.

This facility is also home to two IsotopX Phoenix Thermal Ionization Mass Spectrometers (TIMS), installed in 2016 and 2022, respectively. These instruments are optimized for high-precision isotopic analysis of neodymium and strontium in small-sample matrices relevant to Earth and environmental sciences.

A dedicated mineral preparation lab is also located within the Devlin complex, equipped with tools for crushing, grinding, magnetic separation, and micro-milling of geological materials.

The laboratory at 245 Beacon Street supports stable isotope and trace element analysis. It houses four mass spectrometers:

• A Thermo Delta V Plus Isotope Ratio Mass Spectrometer (IRMS) coupled with a Gas Bench II for automated CO₂ analysis of carbonates and water isotope ratios.
• An Elemental Analyzer (EA) interface for δ¹³C, δ¹⁵N, and δ³⁴S isotopic analysis of solid samples.
• A Thermo 253 Plus IRMS, installed in 2024, configured for high-precision analysis of δ¹⁵N and δ¹⁸O in N₂O using the denitrifier method.
• Agilent 8900 Triple Quadrupole ICP-MS, which can be operated in solution mode or coupled with an Applied Spectra RESOlution 193 nm ArF excimer laser ablation system. This configuration enables high-resolution in situ elemental and isotopic mapping of solid samples, including minerals and glasses.

The laboratory is also equipped with precision drilling devices and a Sartorius microbalance with microgram sensitivity for the accurate preparation and weighing of powdered samples, particularly carbonates.

The Center's first TIMS was installed in 2016. It is equipped with nine moveable Faraday collectors, an ion-counting Daly detector, and a full complement of 10¹¹ and 10¹² Ω resistors, allowing flexible signal detection across a wide dynamic range. In 2022, a second Phoenix TIMS was commissioned, incorporating the latest ATONA amplifier technology, which provides enhanced stability, lower noise, and improved precision for long-duration measurements. This instrument features the same collector configuration—nine moveable Faraday cups and an ion-counting Daly detector—enabling high-precision isotopic analyses even on ultra-low abundance samples.

Both TIMS instruments offer exceptional sensitivity, enabling the acquisition of high-precision isotopic data from sub-nanogram quantities of high-mass elements (e.g., 143Nd/144Nd, 87Sr/86Sr). Long-term external reproducibility routinely achieves better than 15 ppm (2SE), making these systems ideally suited for ultra-low abundance isotopic applications in geochemistry and environmental sciences.

Filament preparation is conducted in-house using an Amada Miyachi spot welder, followed by degassing in a Thermo Fisher DG60 filament outgasser. Sample loading is performed under ULPA-filtered laminar flow conditions at a custom-built filament loading station, ensuring minimal particulate and chemical contamination during handling.

Installed in 2022, the Agilent 8900 is a high-performance triple quadrupole ICP-MS capable of ultra-trace elemental analysis with excellent interference removal using its collision/reaction cell. It supports two analytical modes:

• Solution Mode: Utilizes a peristaltic pump and a 240-position solution autosampler to measure acid-dissolved solutions or filtered water samples with high throughput and precision.
• Laser Ablation Mode: Operated in tandem with the Applied Spectra RESOlution SE 193 nm ArF excimer laser ablation system, this mode enables high-resolution spatial analysis of solid samples. Applications include trace element mapping in minerals, glasses, biological tissues, and synthetic materials.

This dual capability makes the Agilent 8900 an essential part of the Center’s mission to support cutting-edge, interdisciplinary research.

This excimer laser ablation system is coupled directly to the Agilent 8900 ICP-MS and enables high-resolution trace element analysis of solid samples. It supports both:

• Spot analyses for targeted elemental measurements, and
• 2D elemental mapping for spatially resolved imaging at micrometer scales.

These capabilities are especially useful for geochemical, environmental, and materials science applications that require precise localization of trace elements.

This facility is dedicated to the processing of solid geological samples and the isolation of specific mineral phases. It is equipped with a range of tools for sample preparation, including:

• A Cole-Parmer™ Mixer/Mill™ Single-Clamp High-Energy Ball Mill for grinding rock fragments into fine powders
• Petrographic and binocular microscopes for detailed mineral identification and selection
• An exhausting fume hood designed for safe heavy liquid density separation
• A Frantz isodynamic separator (newly installed) for efficient magnetic mineral separation
• A New Wave MicroMill for high-precision microsampling of specific mineral domains

Located in Devlin Hall within the Department of Earth and Environmental Sciences, the SEM facility is a key analytical resource supporting the Center for Isotope Geochemistry. It is equipped with a Tescan Mira 3 Schottky Field Emission SEM, which can operate in both high-vacuum and variable pressure modes.

This versatility enables high-resolution imaging and analysis of a wide range of specimens, including both coated and non-conductive specimens.

This FEG-SEM is equipped with a comprehensive suite of analytical detectors for advanced materials imaging and characterization, including secondary electron (SE), backscatter electron (BSE), and cathodoluminescence (CL) detectors. It also features an integrated Oxford Instruments HKL Symmetry2 Electron Backscatter Diffraction (EBSD) detector and an X-Max 50 Silicon Drift Detector EDS detector. Together, these systems enable the rapid analysis of crystallographic fabrics (i.e., crystallographic preferred orientations), rock microstructures (textural mapping), and the generation of semi-quantitative mineralogical and compositional maps.

Supporting instrumentation for SEM lab includes:

• EMS 150TE turbomolecular-pumped carbon coater – for applying ultra-thin conductive coatings required for SEM, EDS, and EBSD analyses
• Struers LabPol-5 polishing system – for high-quality surface preparation of geological and material samples
• Buehler MiniMet and Vibromet2 polishers – specifically used for precise EBSD sample preparation
• A digital camera-equipped Zeiss Axioskop 40 petrographic microscope and Leica Z6 APO macroscope – for reflected and transmitted light observation and imaging of polished thin sections
• A suite of dedicated workstations – for the post-processing and data analysis.