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Steve:

We have done this, so I have to ask, why are you trying to remove the sediment? Do you have so little that you need a capillary? We just mount the filters; we have special stages for filter or film analysis. You can run a blank filter and substract that scan if you have issues with the background. I haven’t noticed it being too bad with membrane filters; glass fiber filters [which we use when analyzing sediments for stable isotopes – back on topic - ;-) ] do create a large amorphous background. We do use a Co source and a focusing mirror (and spinning stage) to overcome the small sample issues.


David R. Vann, Ph.D.
Dept. Earth & Environmental Science
The University of Pennsylvania
240 S. 33rd St.
Philadelphia, PA 19104-6316
215-898-4906



From: Stable Isotope Geochemistry <[log in to unmask]> On Behalf Of Steve Nelson
Sent: Thursday, September 27, 2018 3:33 PM
To: [log in to unmask]
Subject: [ISOGEOCHEM] off topic but ?relevant? question for smart folks

I’m interested in separating and collecting suspended stream sediments for SEM and XRD analysis.  There’s lots published on measuring concentrations (i.e., mg/L), but little on sediment recovery for futher analysis.

I’ve attempted recovery from 0.45 micron filters (cellulose nitrate) by placing the membranes in an ultrasonic bath.  I can recover enough sediment to ID the minerals by XRD, but the filters clog quite readily and the ultrasonic bath always produces a significant amorphous cellulose background as the membrane breaks apart.

Settling times for the clays will be enormous, but I will have access in the field to a nearby lab with standard centrifuges.

However, has anyone tried using one of the centrifuges used for separating soilds from oil?  They are set up to allow continuous flow of oil (water in my case) and rather than using bottles or tubes the sediment is deposited on the inside of a “bowl”.   While spinning, the sediment doesn’t have far to “fall.”

Any thoughts or other suggestions (offline) would be greatly appreciated.


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Steve Nelson
Professor of Geochemistry
Dept. Geological Sciences
S-389 ESC
Brigham Young University
Provo, UT  84602
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DISCLAIMER FOR THE FEEBLE MINDED:  It should be painfully obvious, but my affiliation with Brigham Young University does NOT imply that the University endorses any political or otherwise partisan content of this message.

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