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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 
__________________________