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
__________________________