ELEMENTAL ANALYSIS

The Earth & Planetary Sciences Department at UC Santa Cruz is fortunate to have a complete set of major and trace element analysis tools with which to measure the elemental composition of solid materials. For major, minor, and some trace elements we have wavelength-dispersive X-ray fluorescence (XRF) for bulk samples, and electron probe micro analysis (EPMA) for spatially-resolved studies. For trace and ultra-trace concentration measurements we have inductively-coupled mass spectrometry (ICPMS). Additionally, we have access to inductively-coupled optical emission spectroscopy (ICPOES), atomic absorption spectrophotometry, ion chromatography, gas chromatography, and gas chromatograph mass spectrometry through the Institute of Marine Sciences Marine Analytical Lab housed in our building.

INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY

Acquired in 1995, our Finnegan Element magnetic-sector ICPMS is still running strong and producing high quality analyses for a wide variety of sample types and users. We maintain a selection of nebulizer and spray chamber configurations including a desolvating nebulizer (Cetac MCN600) and a flow injection system.

This instrument has sensitivities ranging from 10,000 cps/ppb for Li to 3.5 x 10^5 cps/ppb for U at sample flow rates of 40 ul/min, and has a very stable and linear mass response across the periodic table. It can produce isotope ratio analyses with true external precisions in the 0.1% range (within-run precisions are commonly much better).

Linear elemental concentration calibrations have been produced on count rates as low as a few cps, and at concentrations in the ppq range. This is truly a remarkable and versatile instrument which has opened many doors across a broad range of scientific disciplines.

We recently have acquired, on long-term loan from Stanford, a 213 nm New Wave laser ablation system which can be used in conjunction with either our Element or our Neptune mass spectrometers for spatially-resolved elemental or isotopic analysis.

A diverse user group includes marine chemists, hard-rock geochemists, archaeologists, chemists, environmental toxicologists, and paleo-oceanographers, to name a few.

X-RAY FLUORESCENCE ANALYSIS

In the winter of 2006 we replaced our aging AXS (one of the very first automated X-ray fluorescence spectrometers) with a very lightly-used, state-of-the-art XRF, donated by Quadra Mining. Used for only six months in 1998 at the Robinson Mine, Ely, NV, and mothballed for the next seven years, this Philips (now PANalytical) PW2404 comes equipped with a 4KW generator, a sharp-focus end-window Rh tube, an automated 96-sample changer, and a full complement of tube filters, analyzing crystals and detectors. This system utilizes all of the modern methods for spectrometric analysis and data reduction, and is capable of measuring a wide variety of materials, both solid and liquid, for major and trace element concentrations, qualitatively, semi-quantitatively, and quantitatively. Earth & Planetary Sciences at UCSC has been performing XRF analyses of the highest quality for 40 years, and with this new facility we are equipped to continue to do so for many years to come.

ELECTRON PROBE MICROANALYSIS

Our ARL-SEMQ electron microprobe, acquired in 1992, has been upgraded to run on the Advanced Microbeam interface and software, which runs on a PC platform under Windows.

The EPMA system has 9 wavelength-dispersive spectrometers, six fixed and three scanning, which allows for very rapid major and minor element analysis of common silicate minerals (as fast as ten seconds per spot). The unit is also fitted with EDS, as well as secondary, backscattered and cathode-luminescence imaging. The software allows for X-ray mapping based on the output of the wavelength-dispersive detectors, and allows for fully automated analysis using mapped digital shapes, transects, and points. Quality of the elemental analysis data is very high due to rapid analysis time and excellent filament stability.

dsampson@earthsci.ucsc.edu