Dear Erik,


To come up with a satisfactory and useful answer for you, can you tell me a 
bit more about this (off list if you prefer)?

What instrument and, hence what type of combustion reactor are you using?

When you re-oxidised the reactor, at what temperature and for how long?


Best,

Wolfram



On Apr 23 2007, Erik D. Pollock wrote:

>  List Members,
>    I am having an issue with the chromatography going bad after 
> oxidizing the combustion column. Prior to oxiding the column our multi 
> fame house standard has peaks that range from 700 mV to 1300 mV with peak 
> widths of about 20 seconds. After oxidation the same sample has peaks 
> which are less than 100mV to 400mV and widths 35 to 50seconds. The 
> problem is unaffected by GC service, column cutting, new inlet liner, new 
> septa. The unsatisfactory solution is make many standrad injections which 
> slowly improve the chromatography. Has any one had similar issues. I have 
> heard rumors of some folks sending part of a solvent peak through the 
> combustion column? Our GC-C-IRMS set up for FAMEs It is an HP6890 with a 
> Delta Plus and a GCIII combustion interface. The MS seems operating 
> normally, good backgrounds, good refernce peaks, little to no change in 
> these before or after oxidation.
> 
> Erik D Pollock 
>  University of Arkansas Stable Isotope Lab 
> 632 Science and Engineering Hall 
> Fayetteville, AR 72702 
> 479-575-4506 
> http://www.uark.edu/ua/isotope/index.php
>