  |
 |
|
|
||
|
|
|
|
|
||
&delta&13C Run Setup Overview (from Jay Brandes, Skiddaway):Safety WarningSamples for &delta&13C of DIC are often treated with mercuric chloride (HgCl2). Mercuric chloride is extremely toxic! HgCl2 can be absorbed throught the skin. Always wear gloves and eyewear when in contact with DIC samples. Furthermore, be concerned about any potential residues that can end up on the countertops, sinks, secondary containtiners (etc..), and dispose of the used vials with a mind that they can contain fatal concentrations of poison and should not come into contact with humans. 1. Run at 300 microliters/min carrier, 50 ul/min acid, no oxidant. Different flow rates result in slightly different uncorrected isotope numbers, so be consistent. Faster flow rates result in narrower but smaller peaks and slightly degraded standard deviations. 2. Use standard acid concentration, no silver nitrate. More acid does not help. 3. I use the surveyor autosampler and set it up to do 4 replicate injections, every 200 seconds. 25 microliter loop. You could inject less if you wish but I don't see the point in changing it out. I typically take the mean of the last three injections, with the caveat that you should monitor peak areas. The first peak usually is different from the others because of carryover and sample wash issues. An unexpectedly small peak area should be tossed out from the average. You can also use the manual injector, it is more tedious but if you want to run small samples (and you can run 1 uL samples! ) this is the way to go. 4. I have seen no issues with corrosion. I make sure the autosampler is well flushed/washed before and after each run. 5. prefilter your DIC samples through a 0.2 or better syringe filter, taking care to rinse said filter and to fill vial with no turbulence or bubbles. 6. Biggest problem so far has been the autosampler vials. Do not use standard teflon/silicone septa, they allow CO2 degassing and you do see a difference over the course of a few hours. You will want to run standards every 5-10 samples anyway to correct for drift. I use butyl rubber septa but the autosampler has this bad tendency to push the septa into the vial instead of going through it. If it does push the septum down then the first peak will be smaller and garbage isotopically. If you have the ability to cool the autosampler tray I think this will help, but I haven't tried it. 7. I run at 80oC on the ox furnace. I get slightly better results this way. 8. I use water with 1 drop conc. H3PO4 added prior to degassing as carrier. I routinely get 30 mv m/z 44 background levels in the Isolink this way. Degas both carrier and acid as you would for organic samples. I also degas the autosampler wash fluid and use the same 1 drop acid in it. 9. Other issue is standards, best approach is to standardize a bunch of seawater (artificial or otherwise) using the gasbench method and then use this as a secondary standard.     |
 NEWS & EVENTSUCSC's Stable Isotope Laboratory operations are back to full operations following the Covid-19 shutdown. Please contact the lab if you are interested in our services. SIL Co-Director Matt McCarthy directed a weekend program for about 20 Educational Opportunity (EOP) STEM transfer students highlighting the use of stable isotope analyses in phyiscial and biological science inquiry. UCSC's Stable Isotope Laboratory welcomes new Ocean Sciences faculty member Pratigya Polissar. Dr. Polissar will join the SIL as a co-director SIL Co-Founder Paul Koch and colleagues review Sundance Film Festival movies for Science magazine. SIL Co-Director Matt McCarthy recieved a NSF Major Research Instrumentation award for new compound specific isotope ratio mass spectrometers. SIL Co-Director Matt McCarthy directed a weekend program for about 40 Educational Opportunity (EOP) STEM transfer students highlighting the use of stable isotope analyses in phyiscial and biological science inquiry. SIL Co-Director Jim Zachos appointed to Ida Benson Lynn Endowed Chair in Ocean Health. UC Santa Cruz biologists Daniel Costa and Luis Huckstadt found valuable samples for comparison of modern Weddell seals to century-old pelts found in the huts of Antarctic explorers Ernest Shackleton and Robert Falcon Scott. Their findings reveal changes in the Ross Sea ecosystem. SIL Co-director Jim Zachos elected to be a member of the National Academy of Sciences! UCSC Stable Isotope Laboratory data used to show threatened grizzly bears in Yellowstone National Park have a vital hankering for a dwindling supply of pine nuts. SIL Co-director and UCSC Physical and Biological Sciences Dean Paul Koch has been elected 2015 AAAS Fellow for "energetic and innovative leadership in applying stable isotope geochemistry to document and interpret environmental change through the past 65 million years of Earth history.". SIL Co-director Jim Zachos has been awarded the 2016 Milutin Milankovic Medal by the European Geosciences Union. Formation of coastal sea ice in North Pacific drives ocean circulation and climate. So indicates evidence published by UCSC scientists Karla Knudson and Christina Ravelo. Christina Ravelo, Professor of Ocean Sciences at UC Santa Cruz and UCSC Stable Isotope Laboratory co-director, has received the 2013-14 Outstanding Faculty Award from the Division of Physical and Biological Sciences. The annual award is the division's highest honor for faculty achievement, recognizing combined excellence in research, teaching, and service. Long-term human influenced dietary habits of Yosemite National Park black bears explored by UCSC scientist Jack Hopkins, Paul Koch, and colleagues. SIL Co-Director Paul Koch honored as a Fellow of the California Academy of Sciences. See story here. Diversity of great white shark diet was shown to be greater than previously thought based on research by UC Santa Cruz colleagues Sora Kim, Paul Koch, and James Estes along with co-author M. Tim Tinker of the U.S. Geological Survey. This work was highlighted in the Los Angeles Times. SIL Co-Director Paul Koch has been named Dean of the UC Santa Cruz Division of Physical and Biological Sciences. Madagascar Lemur extinctions and ecological retreat followed arrival of humans according to UCSC Graduate Student Brooke Crowley, Professor Paul Koch and co-authors. Their findings were recenlty published in the journal Proceedings of the Royal Society B. SIL Co-Director Paul Koch was quoted in the New York Times on research showing that a tiny Paleocene horse Sifrhippus, the first horse, grew even smaller during the Paleocene-Eocene Thermal Maximum climatic warming event. SIL Co-Director Christina Ravelo has been selected as an American Geophysical Union (AGU) Fellow. SIL Co-Directors Paul Koch and Jim Zachos's research on Paleocene-Eocene Thermal Maximum (PETM) climatic warming event is featured in an National Geographic article "Earth Before the Ice" in the October 2011 issue. SIL Co-Director Paul Koch has been appointed Interim Dean of the UC Santa Cruz Division of Physical and Biological Sciences. SIL Co-Director Jim Zachos elected to the American Academy of Arts and Sciences. UCSC's SIL new ThermoScientific MAT 253 isotope ratio mass spectrometer coupled to a Kiel Automated Carbonate Device begins regular operations. UCSC's SIL retires its 15 year-old dual-inlet Optima following a very productive career. The instrument generated over 40,000 data points. Two Tsavo Lions In Famed Killings Get Partial Reprieve according to UCSC Graduate Student Justin Yeakel. Listen to Justin's inteview on National Public Radio's All Things Considered: SIL co-director Christina Ravelo (Ocean Sciences) sails as co-chief scientist on Integrated Ocean Drilling Project (IODP) Expedition 323 to investigate Bearing Sea Paleoceanography.
SIL co-director Christina Ravelo (Ocean Sciences) gives the 2008 Emiliani Lecture at the American Geophysical Union Meeting in San Francisco on "Lessons from the Pliocene Warm Period and the Onset of Northern Hemisphere Glaciation".
UCSC SIL has been funded by the National Science Foundation for a new Dual-Inlet Isotope Ratio Mass Spectrometer with individual acid drip system for very small calcium carbonate samples. SIL co-director Jim Zachos (Earth and Planetary Sciences) recieves prestigious Humbolt Research Award. See Humbolt Award for details. SIL Co-Director Jim Zachos has been selected as an American Geophysical Union (AGU) Fellow. In recognition of the new continuous flow instruments added to the UCSC stable isotope facility a Symposium is being run to highlight the new analytical capabilities. |
