A TEAM-REU TO DEVELOP LABORATORY PROTOCOLS TO ENABLE THE U-SERIES DISEQUILIBRIA DATING OF GEOLOGICAL AND BIOLOGICAL SAMPLES USING PLASMA SPECTROMETRY

As part of a cohort learning experience, a group of transfer students from Linn-Benton Community College, Oregon, conducted a 2018 summer research experience for undergraduates as part of a bridge program (LBOS-Geobridge). This program placed four students in the W.M. Keck Collaboratory for Plasma Spectrometry in the College of Earth, Ocean, and Atmospheric Sciences at Oregon State University. The project goal was to develop laboratory protocols capable of separating and purifying U and Th from natural materials to enable the dating of geological and biological samples using U-series disequilibria. Specifically, this project has resulted in the development of laboratory protocols for the column separation of U and Th isotope dilution (ID) and isotopic compositions (IC). In addition, mass-spectrometry techniques have been investigated and optimized for the measurement of U/Th ID utilizing a ThermoScientific X-Series II quadrupole ICP-MS and U/Th IC utilizing a Nu Instruments 3D multi-collector ICP-MS.

Through this experience, the four students have been trained in the general practices for working in a clean lab. This includes pipetting, making and titrating different strength acids, and cleaning laboratory space and consumables. They have also learned to calibrate and run chromatographic columns, and have a basic understanding of isotope dilution and why it is used. The four students are proficient working with, and communicating the difference between, concentrations and absolute quantities (e.g. ppb versus ng). The students all calculated and prepared a standard calibration block for regression analysis and quantification by ICP-MS and they operated the quadrupole ICP-MS.