GC (MS) problem with tailing peaks

[Ron]

Ok, the area being roughly constant pretty well eliminates the possibility of a leak, so now we are back to basic chromatography issues. At this point the best thing seems to be to clip the inlet end of the column, and dropping the bottom of the injection port to see if there is contamination there as Peter suggests is a good idea. The seal is not designed to be reused, and may leak if you try to reuse it. I would suggest not opening up the bottom of the port until you have a replacement seal. Restek makes seals with a Vespel sealing surface that are easier to seal up than the standard Agilent parts.

[soccerdad007]

I wanted to bring everyone up to date.

We trimmed about 10cm off the end of the column and everything seems to be okay.

We managed to get it working 5 mins before my class was due to start... so things were pretty frantic for a while there.

Part of me is curious why
1. The problem was worse for the higher alkanes
2. The problem improved a little after we changed liner (just for the first run)

Part of me (the dominant part) just wants to get on and use the GC-MS and not worry about the whys!!

To all who replied - thanks for all the help. I have increased my inlet temperature as several of you suggested and right now everything is working great

Kevin[/list]

[Peter Apps]

Hi Kevin

Thanks for the feedback. In general higher boilers are worse affected by any absorbtive or adsorptive activity. Are you running isothermal ?

First run improvement ? Possibly some dirt in the inlet and then a progressive deterioration of the column tip ????

Peter