Carrier gas for split injection

Chromatography Forum: GC Archives: Carrier gas for split injection
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Dave Wolff on Monday, November 10, 2003 - 05:11 am:

Hi - I'm new to GC's and I'm trying to see if my hydrogen generator will supply enough gas for split injection. When using split injection, how long is the split vent typically open - just a little while during injection (hence less than a minute or so), or longer (a significant part of the run)? If the split vent is open only a short amount of time, I've got plenty of capacity, but if it is open a long time, then I've got limitations.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Monday, November 10, 2003 - 06:45 am:

Typically for split injections the split vent is open the entire time. In splitless, it's closed at first then comes on at programmed time.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Monday, November 10, 2003 - 10:46 am:

If the split flow is very high, like if you're running a 100 :1 split, then you are wasting a lot of carrier gas. If your instrument has a gas saver function, then you could program it to close the split vent after a period of time, say 1 to 5 minutes. You can experimentally determine how long the split needs to be on.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Bernd Mischke on Thursday, November 13, 2003 - 04:53 am:

In split injection the split-vent is always open! After the injection You should clean the injector with carrķer gas, if Your sample concentration is high, than over a longer time. After few minutes You can use the "gas saver" but it dosn't close the vent complete - reduce the flow to 20...30ml/min.
If You have any question - sent it to me


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