Cold on column injection

Chromatography Forum: GC Archives: Cold on column injection
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, January 3, 2003 - 02:53 am:

Cold on column injection.
Could anybody explain this?
Is it possible to use it with any GC?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Friday, January 3, 2003 - 10:00 am:

Typically, a split/splitless injector is used in GC. In this case the sample is injected into a hot injection port (e.g. 280 C). The samples is vaporized in the injection port liner and swept onto the column by the carrier gas flow. A cold on column injection deposits the sample directly into a cold (e.g. 40 C) column. The sample is vaporized and moves through the column during the temperature ramp.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Dodo on Tuesday, January 14, 2003 - 01:11 am:

May I know what is the advantage of using this cold column injection. Are there any different between cold column and on column injection?


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Tuesday, January 14, 2003 - 02:55 am:

The term cold on-column injection was introduced for capillary GC to distinguish it from {hot)or simply "on-column injection" which had been used for many years in packed column GC. For packed columns, the space above the packing is usually (but not always!) large enough to act as a vaporising chamber for the volatilised sample. If you inject hot onto a capillary column, the explosive evaporation of the sample may not be contained, causing backflush of the sample out of the column. Thus, the injection is usually made cold so that the sample can gradually vaporise. Cold injections have other advantages, since they avoid syringe needle discrimination. However, the presence of initially unvaporised liquid in the column can introduce all sorts of other problems.

Dodo-I'm glad to see that you are alive and well, and not at all extinct!

David McCalley


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Dodo on Wednesday, January 29, 2003 - 06:29 pm:

Dear David,

Thanks for the explanation.

However, u might be a little bit sad to know that I bore little resemblance to my big and furry ancestor *_^

Dodo


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