We use a GC-PAL autosampler from CTC for
the waters. I also observe that the syringes seem to take a day or so just
to stabilize the consistency of their peaks.
The mass spec is impeccable during these
transitions and gives great data on our standard gases, so it must be in
the TC/EA somewhere.
Matt
Matthew S. Lachniet, Ph.D.
Department of Geoscience
University of Nevada
Las Vegas, NV 89154
[log in to unmask]
702.895.4388 (office), 702.895.4064 (fax)
From:
Marilyn Fogel <[log in to unmask]>
To:
[log in to unmask]
Date:
06/29/2011 09:06 AM
Subject:
Re: [ISOGEOCHEM]
TC/EA reactor cleaning
Sent by:
Stable Isotope
Geochemistry <[log in to unmask]>
Interesting to read these. We don't have this problem.
Clean it out late afternoon, reassemble, turn on low overnight, then start
running samples in the morning.
What type of autosampler are you using? We've switched
to Costech Zero Blank autosampler which solved a lot of our blank and run-in
problems.
Marilyn
On Jun 29, 2011, at 11:56 AM, Matthew Lachniet wrote:
We've had this same problem. And I've
always just accepted that a minimum of two days is required after starting
the TC/EA and running samples to get good data and switching from other
peripherals. And this is with either new reactors/chips/ceramic tubes,
or old ones. The problem always is there.
Hope someone has a solution.
Matt
Matthew S. Lachniet, Ph.D.
Department of Geoscience
University of Nevada
Las Vegas, NV 89154
[log in to unmask]
702.895.4388 (office), 702.895.4064 (fax)
From: Luisa
Stellato <[log in to unmask]>
To: [log in to unmask]
Date: 06/29/2011
02:29 AM
Subject: [ISOGEOCHEM]
TC/EA reactor cleaning
Sent by: Stable
Isotope Geochemistry <[log in to unmask]>
Hello everybody,
Do you know if there is a method to speed up the cleaning of the TC/EA
reactor after the temperature of the furnace is at 1450°C?
When I set up the system (TC/EA-IRMS) to begin a new session of measurements
in continuous flow, while the water background signal goes down to about
300 mV in one day (mass 40 is about 30 mV), the CO signal (masses 28, 29
and 30) rises till 1400-1500 mV, after the temperature is more than 1250°C,
and then starts to go down very slowly (in about 48 hours at 1450°C
it reaches about 200-300 mV).
I was wondering if there is a method to speed up the cleaning of the reactor
and the reagents (glassy carbon chips), also off-line, to reduce this “dead-time”
and also Helium consumption.
Of course, if I increase the Helium pressure (for example from 1.5 bar
to 1.7 bar on the manometer of the TC/EA) the process is more rapid, but
not so much.
Thank you to all who have an advice for that.
Cheers,
Luisa
_________________________
Luisa Stellato, PhD
Groundwater Research Centre
Dipartimento Scienze e Tecnologie
per l’Ambiente e il Territorio
Università degli Studi del Molise
Contrada Fonte Lappone
86090 Pesche (IS), Italy
tel: +39 3476037825
web: http://www.distat.unimol.it/STAT/groundwater-research-centre/english
__________________________