| Boise State Isotope Geology Laboratory LABSHARE | |||||||||||||||||
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| Department of Geosciences | |||||||||||||||||
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The BSU IGL is a node in the EARTHTIME Network for the Calibration of Earth History. In the spirit of teamwork and cooperation fostered by the EARTHTIME Labshare initiative, please take a look at our developing archive of analytical procedures used in the BSU IGL for isotope geochemistry and geochronology*.
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| Boise State University | |||||||||||||||||
| Math/Geo 207 | |||||||||||||||||
| 1910 University Drive | |||||||||||||||||
| Boise, ID 83725 | |||||||||||||||||
| tel: (208) 426-5907 | |||||||||||||||||
| fax: (208) 426-4061 | |||||||||||||||||
| *Disclaimer: While the information below represents the accumulated knowledge and practices used in the BSU IGL, the laboratory and affilitated staff are not responsible nor liable for errors of omission or otherwise. Procedures are always being refined, so these files are periodically updated. | |||||||||||||||||
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Helpful Hints! |
last updated, 09/02/09
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| Supplier for pucks and stems for "nanocapsules"... Jeremy Hourigan of U.C. Santa Cruz (hourigan@ucsc.edu) has graciously contributed a set of plans for the nanocapsule holders (shown below under Shop Drawings) drafted with the e-machineshop.com <http://www.emachineshop.com/> CAD program; this service looks like a great deal for those who don't have ready access to a local machine shop (Hourigan_puck.ems) (Hourigan_puckholder.ems) | |||||||||||||||||
| Teflon cleaning... we have found that the most efficient and effective way to clean Savillex teflon (particularly capsules for zircon dissolution) is to alternate concentrated HF (220°C) and concentrated HCl (180°C), 48 hours each for numerous iterations. This appears to "pump" trace metals out of the resin much more effectively than other more dilute acid treatments. For example, capsules cleaned for several months with alternating HF and 6M HCl which consistently yielded 2-3 pg Pb blanks, when exposed to this new method liberated pulses of tens of pg's of Pb after each HF step, and now yield capsule blanks indistinguishable from loading blanks (0.2 pg Pb). | |||||||||||||||||
| Our internal lab supplies database... (IGL Laboratory Supplies) | |||||||||||||||||
| Mass spec cleanup... we routinely boil the stainless steel portions of our turret, bead blocks, ion source lens, and filament beads in ACS-grade hydrogen peroxide to effectively remove Re buildup (no scrubbing of slit plates or filing of used filament beads needed!) and oxidize residual organics. The method is described in Mass spectrometry handbook.
After a periodic cleaning and reassembly of a full turret and hats, we will also load a set of outgassed Re centers into the blocks and run each one up to 4A for 30 minutes in the mass spec (an overnight automated process) to heat the block and hats up; we find that this mitigates generally isobaric interferences on mass 204 (and other isotopes to lesser degree) which are usually more intense on the first turret post-cleaning. |
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Data Reduction |
last updated, 10/24/08
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| Schmitz, M. D. and Schoene, B. (2007) Derivation of Isotope Ratios, Errors and Error Correlations for U-Pb Geochronology Using 205Pb-235U-(233U)-Spiked Isotope Dilution Thermal Ionization Mass Spectrometric Data, GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, VOL. 8, Q08006, doi:10.1029/2006GC001492. (reprint) (spreadsheet) | |||||||||||||||||
| Note that in the pdf of Schmitz and Schoene, Table 1 was partially compromised by omission of the abbreviations for tracer isotope ratios. All tracer isotope ratios end in "t", e.g. "R85t" is the tracer 238U/235U. All measured ratios (partly mislabeled in Table 1) end in "m", e.g. "R85m" is the measured 238U/235U. | |||||||||||||||||
| * Next generation Excel-based spreadsheet ID-TIMS U-Pb data reduction using the algorithms of Schmitz and Schoene (2007), now including ability to use all mixed 202Pb-205Pb-233U-235U-236U spikes, as well as earlier Th/U corrections, geochemical parameter calculations and formatted data table generation. (YourLab_UPbR_AnySpike.xls) (Alternative_Spike_Eqns.pdf) | |||||||||||||||||
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last updated, 11/04/08
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| Pb-MacDat 2007 —this version corrects an error in the calculation of 206Pb*/238U ratio errors found in Ludwig's original PB-DAT source code; view Clark Isachsen's tutorial on the use of Pb-MacDat on the EARTHTIME Labshare page. | |||||||||||||||||
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Mass Spectrometry |
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| Mass spectrometry handbook |
last updated, 05/06/09
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last updated, 02/13/07
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| Silica gel preparation & cleaning | |||||||||||||||||
| Uranium oxide correction for 233U-235U spiked samples |
last updated, 02/13/07
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| Uranium oxide composition determination method (courtesy of Dan Condon, NIGL, UK) |
last updated, 11/05/08
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| Laboratory Methods | |||||||||||||||||
| Mineral separations handbook |
last updated, 08/14/08
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last updated, 05/06/09
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| General clean lab handbook | |||||||||||||||||
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last updated, 05/06/09
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| Column chemistry handbook | |||||||||||||||||
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last updated, 08/14/08
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| U-Th-Pb accessory mineral handbook | |||||||||||||||||
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Shop Drawings |
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last updated, 07/17/07
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| Stem and puck holder for "Ludwig"-type PFA microcapsules, for accessory mineral dissolution | |||||||||||||||||
| Polypropylene stand for a double quartz sub-boiling still (still supplied by Allen Scientific Glass) | |||||||||||||||||
| Polypropylene stand for a double PFA sub-boiling still (still supplied by Savillex Corp.) | |||||||||||||||||
| Zircon air abrader (GSC/MIT style) (designed by Clark Isachsen, U. Arizona) | |||||||||||||||||
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