Hi Nico,



Changing to a lower ID column coated with the same stationary phase (of the same film thickness) will chiefly affect separation (for the better).


Sample volume per se is determined by injection conditions and net volume of the injector (injector liner).


Sample load as in actual amount of compound(s) present in a sample and ending up on column, i.e. how much a column with tolerate before showing signs of overload (broad, front-tailing peaks) is primarily a function of film thickness.  In other words, going from 0.32 down to 0.25 ID will not affect sample concentration that can be safely injected provided column parameters such as stationary phase and film thickness stay the same. 


The last info I have on file concerning PLOT column, the difference in film thickness between an 0.25 mm and an 0.32 mm Pora-PLOT Q is relatively small (8 micron compared to 10 micron respectively).  For the Pora-BOND Q columns with 0.25 and 0.32 ID the corresponding film thickness values are 3 micron versus 5 micron respectively. So, here one should start with injecting samples with a slightly lower compound concentration (or less sample volume).









From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf Of Küter Nico
Sent: 06 January 2017 16:07
To: [log in to unmask]
Subject: [ISOGEOCHEM] AW: [ISOGEOCHEM] Separation of CO and N2 in a GC


Thanks a lot for the very helpful answers!


@Wolfram: I will look into the PorabondQ’s. The hint with the smaller diameter was very helpful. Agilent is offering a PoraPLOT Q with 0.25mm and 25m length, and seemingly also offers longer columns if needed. So far, I only worked with 0.32 ID columns. Is there anything that is changing drastically and that I should keep in mind when switching to a smaller ID, analytical-wise? I guess the sample volumes have to be smaller?

By the way, I usually inject manually 50 to 300 ul gas that contains around 1% CH4-CO2-CO mix diluted in He. The gas compounds vary strongly in concentration.


@Herb: Thanks, I look into the GS-GasPro!


@Klaus & Robert: The Carboxen1010 column sounds indeed very interesting! Almost too good to be true. Probably very much worth a try! Robert you mentioned the CO2-sorbtion problem, something I was quite afraid of when I saw that this column is operated at quite high temperatures. However, Klaus wrote me that he has good experiences with the column in separating CO2 and CH4. I definitely keep the Column in mind!


All the best,




Institute for Geochemistry and Petrology
ETH Zürich
NW E-75.1
Clausiusstrasse 25
8092 Zürich

Von: Stable Isotope Geochemistry [[log in to unmask]]" im Auftrag von "Robert Panetta [[log in to unmask]]
Gesendet: Freitag, 6. Januar 2017 15:04
An: [log in to unmask]
Betreff: Re: [ISOGEOCHEM] Separation of CO and N2 in a GC

Dear Nico,

A mole sieve column will certainly do the trick for N2-CO at above ambient. But CO2 sorbs strongly to a mole sieve (you'll need to get above 450 oC to take it all off the column in a reasonable time frame).

That's where a carbon mole sieve of the kind Klaus mentioned comes in handy. It will seperate all the permanent gases at non-cryogenic temperatures, and some permutations will perform well with light hydrocarbons too. It's best to contact the manufacturers (i.e., Agilent, Sigma and Restek) with your requirements and see if they have a suitable column for both permanent gases and light hydrocarbons.

Good luck!




On Thu, Jan 5, 2017 at 7:00 AM, Dr. Klaus-Holger Knorr <[log in to unmask]> wrote:

Dear Nico,
we use a Supelco / Sigma Aldrich Carboxen 1010 PLOT column (0.32 ID, 30 m) for separation of permanent gases, such as O2, N2, CH4, CO2. It would also separate CO and the retention time is clearly deviating from the timing of N2. The column also separates O2 and N2 if operated at 30 °C


Am 05.01.2017 um 12:38 schrieb Herbert Tobias:

Hi Nico,


Just to put out an unconventional choice of column to try is the GS-GasPro (Agilent). I do not know how it would handle large amounts of CO and N2, etc... but I have used it for excellent separations of CO and C2H6, CO2, and other natural gas products from pyrolyotic processes. 





On Jan 5, 2017 5:38 AM, "Küter Nico" <[log in to unmask]> wrote:

Dear Community,


We are curious about an efficient way for separating N2 from CO in a GC to analyze CO for d13C and concentration.


We are already able to separate the species somewhat sufficient with 1) an Agilent 30m GC Carbonplot (0.32mm widebore, 1.5um film) by pushing it far below its lower temperature-limit (-70°C) and 2) quite well with an Agilent 50m PoraplotQ  (0.32mm widebore, 10um film, also at -70°C).  We use a HP 6890 GC that is coupled to a Delta V IRMS.


The important point is that we also need to analyze coexisting CO2, CH4 and C2H6. So these should not get lost during the separation process.


Again, the Poraplot Q does a good job, but we are curious if anyone in this community has experience with other columns or with the N2-CO separation in a GC in general.


Thanks a lot and best wishes for the New Year!




Nico Kueter
Institute for Geochemistry and Petrology
ETH Zürich
NW E-75.1
Clausiusstrasse 25
8092 Zürich



Dr. Klaus-Holger Knorr
Dipl. Geoecology Univ.
Institute for Landscape Ecology
Ecohydrology and Biogeochemistry Group
Heisenbergstr. 2
University of Münster
48149 Münster
Mail: [log in to unmask]
Phone: +49-251-83-30207




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