143x Filetype PPT File size 2.74 MB Source: www.snolab.ca
Drivers behind geo- and cosmochemical analysis Desire to analyze sub- nanogram quantities of implanted solar wind, returned cometary material, dust in Antarctic ice, etc. Analytic equipment: SIMS Secondary ion mass spectrometer Pros: Ideal for in situ analysis, quasi non- destructive, high spatial resolution, high mass resolution, for some elements ppt detection limits Cons: sample in ultra-high vacuum, requires perfect surface for ppt analysis, matrix effects, slow, and $ Analytic equipment: ICP-MS Inductively coupled plasma mass spectrometer Pros: ppq detection limits, can work in situ or analyze digests, samples at atmospheric P, matrix insensitive, fast, relatively inexpensive Cons: destructive, requires more material than SIMS, prone to blank contamination during sample preparation, may require elemental pre- concentration Solution ICP-MS Instrumental limits: ICP-MS Sensitivity: 450,000 cps ppb-1 Detection limit: 1 cps Consumed mass: 2 grams Absolute mass of detected material: 4-5 femtograms (10-15g) Dilution factor (solution/solid ratio): 1,000 Hence in 2 g of solution, only 2 mg of solid translates to minimum detectable concentration -1 of 4-5 nanograms g (ppt)
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