Chromatography Forum

Hi all; We are currently investigating the possibility of using two columns in line, connected with a press fit connector, to determine volatile and semi volatile components. I have heard of GC*GC but I think it requires special software and a modulator. If i go ahead and juct connect two columns together what benefits and what problems should i expect? To be more specific the idea is to connect a non polar with a wax column to get better separation say 10 m of non polar and 30 meters of wax. I think usually people use the modulator to focus the analytes at the end of the first column and get sharper peaks. Can i do without the modulator. in our system we have a valco valve. Could i usilise the valve to focus the analytes?Could you recomend a couple of papers for some reading. all the papers that i found so far use the modulator.

To do GCxGC (comprehensive GC) you have to have a modulator between the columns.

With just a connector between the columns you can fine tune the slectivity of the separation by: changing the length of each column, the film thickness of each column, the flow rate or the temperature programme.

If you have a selectivity problem, samples that are consistent in their composition, and a fair bit of time for method development, coupling two columns can be a straighforward way of setting up a standard method for getting peaks separated. Before you go that route I would check all the column manufacturers web sites to make sure that they do not already make a column that can do the separation that you are looking for.

Most of the work on series couple columns was done pre-internet publishing, but you can chexk out, and follow the trail back:

http://www3.interscience.wiley.com/cgi- ... 1&SRETRY=0

http://www.lcgceurope.com/lcgceurope/da ... rticle.pdf

Good luck

Peter

Peter,

Hi, thank you for posting these links as it looks like something I want to try as well (as we were 'discussing' a fortnight ago. I cannot open the first link though, can you please repost it?



Thanks,

Salma

Hi

Sorry about the link - I cannot open it now either.

Try a Google (or similar) search using "gas chromatography", "series coupled", "selectivity tuning" and similar. If you have Science Direct or Ebsco or a simialr scientific search engine you could try them too, but a lot of the literature is from the very early days of GC and it is over the search horizon for some of the databases.

Good luck

Peter