We had exactly the same problems with external samples we had not prepared ourselves. Problem samples included certain type of soil samples, samples that had been HCl acidified, and marine samples. In addition to quartz inserts fusing with the reactor, the reactors developed pin-prick holes through which molten tin tears escaped. Essentially what happens is that contaminants such as alkali and earth alkaline cations will ‘migrate’ into the quartz glass (pure SiOx) forming weaker metal-O bonds which in turn lowers softening point and melting point of the now no longer pure quartz glass.
With the help of Stuart Carter at OEA Labs we developed an insert made of Inconel which “solved” this problem by circumventing it. We presented this as a poster at the 2013 EGU in Vienna. Contact Stuart at [log in to unmask]. I am sure he will be able to help.
From: Stable Isotope Geochemistry [mailto:[log in to unmask]]
On Behalf Of Jeff Havig
Sent: 19 February 2017 19:07
To: [log in to unmask]
Subject: [ISOGEOCHEM] EA insert fusing to oxidation column
Hello Analytical Experts-
I am running a Costech Elemental Analyzer attached to a Delta V Advantage IR-MS, and have been having issues with the combustion chamber quartz insert fusing to the oxidation column (we have had to the replace the oxidation column three times now because of this, and this is less than ideal).
The insert has ~ 1 cm of quartz wool at the bottom with ~2-3 mm of Chromium(III) oxide on top of that. I have been using the medium (5x9 mm) tin capsules for loading samples (49 per run, 2 to 3 runs per insert). The samples I have been running include volcanically-derived glacial sediments, snow algae, and hot spring biofilms (mostly composed of amorphous silica). Some of the samples have been acidified with HCl to remove DIC and carbonates, but have all been rinsed with 18.2 MOhm/cm water to remove all Cl- before drying and grinding.
It seems as though the insert quartz is fluxing and being stripped away, enlarging the slit openings and weakening the insert, allowing the tin to leave the side slits and fuse the insert to the inside wall of the oxidation column. Also, there seems to be a tendency for yellow-ish melt/precipitate to form at the bottom of the insert, fusing it to the oxidation column there as well. I have attached an image (pdf) of the last failure with examples of what I am trying to describe.
The temperature of the combustion chamber/oxidation chamber is at 1000 C (checked with thermocouple). This has happened a few times in the past, but never consistently like this.
If any of you happen to have had this problem and might know 1) what is going on, and 2) the best way to fix the problem, I would be eternally grateful for your time and help.
Jeff Havig, Ph.D.
Department of Geology
McMicken College of Arts and Sciences
University of Cincinnati
Cincinnati, OH 45221-0013
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