Chromatography Forum

Equipment: GC Agilent 7890, Gerstel MPS 2 CTC Autosampler. FID Detector with He carrier gas on a BD Wax 30 x 520 x 1 column

I am having probelms with the calibration of this GC. I have got 6 Ethylene oxide standards in a nitrogen balance between 5 and 100ppm. Can anyone help me with how I can get a good calibration. I don't know whether to do a split or splitless injection, if a split then what split should I use. What injection volume should i use, what temperatures should my detector, injector and oven be at. Please, please, please can someone help me.

Peter

phardy,

Because you are talking about headspace, can I suggest a different approach. Restek, for one, has ethylene oxide in DMSO that could easily be used as a headspace standard. If you put an aliquot of the standard in the liquid you are doing headspace on you can then establish an partition and calibrate based on that.

Regarding split/splitless, if you have the sensitivity, then split will provide you with more flow to sweep the system and generally better peak shape. On a 0.53 you already have quite a bit of column flow so you don't need a very high split, perhaps only 2:1 or 5:1. Injector and detector temps should be at or below the isothermal limits of your column and then experiment. Regarding oven conditions, I cannot help other than to say start cool, say 38C or 42C and hold for a few minutes then ramp at 8-10C/min up to isothermal column limit. See what the chromatogram looks like.

Once you have a starting point, re-post and people on the forum can provide all sorts of advice. Good luck.

Best regards.