Brown University Mass Spectrometry Home Page
The ESH group at Brown maintains three isotope ratios mass spectrometers for analyzing the oxygen, carbon, hydrogen, nitrogen isotopic composition of organic matter, organic compounds, carbonates, and waters. Our mass spectrometry facilities are thus among the best in the world.
MAT 252 ISOTOPE RATIO MASS SPECTROMETER
A new Finnigan MAT 252 with an automated Kiel III carbonate device became operational in January 2001 and is available for internal and external users. This instrument replaced our SIRA-24 on which we processed over 90,000 samples between 1983 and 2000. The MAT 252 is capable of processing 46 samples (including standards) in approximately 26 hours. All analyses are reduced and reported relative to VPDB by calibration to NBS19 reference material. In addition to NBS19 we run two dry lab standards, BYM (Brown Yule Marble) and Carrara Marble. Our long-term analyses of these standards (between 25 and 150 micrograms CaCO3) indicate a routine precision of better than ±0.03 o/oo (1s) for carbon and ±0.06 o/oo (1s) for oxygen.
We generate our reference gas in-house on a vacuum extraction line. Reference gas generation requires ~5 grams of CaCO3 per liter of gas. We typically use the coarse fraction (> 150 microns) from carbonate-rich Pleistocene deep-sea sediments as reference gas material. This generates reference gas sufficiently close in isotopic composition to the marine samples typically run in the lab.
Analyses in progress can be viewed from any web browser at http://188.8.131.52
FORAMINIFER SAMPLE PREPARATION
The number of individual forams required for an analysis depends on the size fraction analyzed. A single benthic foram is typically enough for a reliable analysis. Planktonic forams typically require more than one specimen although single specimen analyses can be run on larger size fractions.
Pre-cleaning procedures vary from investigator to investigator and lab to lab depending on the nature of the samples. Variations of three basic procedures are common. All three procedures are available in the lab.
1. Sonification in H2O
2. Soak in dilute H2O2 followed by a sonification and rinse in ethanol
3. Roasting under vacuum
INFORMATION FOR SUBMITTING SAMPLES FOR ANALYSIS
Foraminifer samples should be submitted in 1- or 4-hole micropaleontology slides with one sample per hole. Each hole/sample should be labeled with the full core and sample identification, Genus and Species identification, size fraction, and the # of individuals. For Ocean Drilling Program samples, the full core sample ID includes the Site, Hole, Core, Core-type, Section and Section Depth in cm.
Examples of how to label each individual sample:
|Core/Sample ID||Genus/Species||Size Fraction (microns)||#of Individuals|
|1146B 19H 3 22||G. sacculifer||300-355||12|
|KNR180 2 55 PC||G. bulloides||200-255||14|
Sample presentation other than 1- and 4-hole slides are also acceptable provided that each sample is appropriately identified as above.
The per sample rate for outside users is $17 per sample. The name and contact information of the principal investigator as well as a purchase order number must accompany submitted samples.
Ship samples to:
Dr. Steven Clemens
324 Brook Street
Providence RI 02912-1846
Phone (401) 863-1964
Fax (401) 863-2058