This is very timely as I have run my first batch of freshwater POM
samples with very low N on our Costech ECS4010 (DeltaPlus XP) and found
that the first two inserts came out fine after about 100 burns (about
8cm of ash build-up) but when I pulled the third insert out of the
combustion tube, there was nothing in it. I am assuming they melted
into the combustion tube? I was also finding my 13C values widely
erratic. Does this have anything to do with the sample meltdown?
A few, maybe related or not questions:
My filament readings were bouncing around the last couple of weeks and
finally burned out today. Would this have something to do with the
erratic 13C (and sometimes 15N)?
And a simple chromatographic problem.......I cannot seem to get my peak
start of CO2 away from the end of the peak jump settling which I think
is sometimes contributing to my varied 13C numbers. My peaks are fairly
close, yet fully resolved so my peak jump timing is pretty critical. (I
am also going to possibly work on the flow rate too for better
separation but I'm already at a low of 90ml/min). I think it's an
integration parameter thing but I haven't found the right settings.
Suggestions please.
Thanks, Anne
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Anne M. Cotter
U.S. Environmental Protection Agency
Mid-Continent Ecology Division
6201 Congdon Blvd
Duluth, MN 55804
218-529-5183
fax 218-529-5003
[log in to unmask]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Shapna Mazumder
<[log in to unmask]
> To
Sent by: Stable [log in to unmask]
Isotope cc
Geochemistry
<ISOGEOCHEM@list Subject
.uvm.edu> Re: [ISOGEOCHEM] filter problems
04/04/2008 11:45
AM
Please respond
to
Stable Isotope
Geochemistry
<ISOGEOCHEM@list
.uvm.edu>
Gerald,
We run freshwater POM filters quite regularly on our Costech-Delta V. I
have found that if samples have been acidified with HCl, the quartz
insert
and column takes a beating. A plug of silver wool below the quartz wool
in
the insert helps. I just run ~25 samples and change the insert to avoid
deterioration in the columns. Hope this helps.
Shapna
Water and Aquatic Sciences Research Program
University of Victoria, Department of Biology
PO Box 3020, Station CSC,
Victoria, BC, Canada V8W 3N5
(250) 472-4789
[log in to unmask]
www.uvic.ca/water
----- Original Message -----
From: "Gerard Olack" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, April 04, 2008 9:28 AM
Subject: [ISOGEOCHEM] filter problems
> Hi All--
>
> We've been running some filters samples on a Costech ECS4010--fresh
water
> phytoplankton. Supposedly these are fresh water, no preservatives,
and
> filtered through standard glass fiber filters. However we've had
problems
> with those samples eating holes in the quartz ash collector, the
quartz
> wool, and sometimes the quartz reactor tube too. In the short term,
extra
> quartz wool and an extra quartz tube in the ash collector minimizes
> damage.
>
> Has anyone else seen this, and if so, have you been able to trace the
> source of the problems? We've done other filter samples without
unusual
> problems.
> take care
>
> gerry
>
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