Print

Print


Hi Jeff,
I don't know if this will be helpful or not, but I use a chromium "buffer"
(~1/2 cm) below the insert in the oxidation column. And I change the insert
every run.
Sorry if this is redundant, I didn't check the entire thread.
Lora


On Sun, Feb 19, 2017 at 2:06 PM, Jeff Havig <[log in to unmask]> wrote:

> 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).
>
> Our setup:
> 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
>
> --
> Jeff Havig, Ph.D.
> Adjunct Faculty
> Room 517
> Geology-Physics Building
> Department of Geology
> McMicken College of Arts and Sciences
> University of Cincinnati
> Cincinnati, OH 45221-0013
>
>
> MAD EGG LAB Website <http://www.jeffhavig.com>
>
> https://scholar.google.com/citations?hl=en&user=wMfFwp8AAAAJ
>
>
> "There comes a time in every mans life where he has to look the potato of
> injustice right in the eye!"
>
> - Stanley Spadowsky, UHF
>
> "Always with the negative waves Moriarty, always with the negative waves."
>
> -Oddball, Kelly's Heroes
>



-- 
Lora L. Wingate
University of Michigan
Department of Earth and Environmental Sciences
Stable Isotope Laboratory
1013 C.C. Little Building
1100 North University
Ann Arbor, MI 48109-1005

phone:  734-763-0561