Chromatography Forum

Florian,

Before I can give you a list of parts to order, we will need to know what columns you are going to use. We will also need to know what the concentration levels are, as this will decide which detector you will have to buy. You can not use your FID for measuring oxygen, so you will need another detector, either a TCD or a Helium ionisation detector.

I stress again the need to know the concentration levels as this will decide on the correct hardware. Low ppm and ppb levels of oxygen need very special hardware due to oxygen from the air diffusing into the system.

Gasman

Hello Gasman,

Unfortunately I don't know yet, which amount I will have to detect. But I'd like to make two suggestions for my ADC colleagues. Using the GC, for which I would need a new detector, column, valve and eventually inlet. With this option detection down to 100 ppm should be enough. If this level is not sufficient, I would suggest a gas detector, which is probably more expensive.

In the J&W programm I found the following columns, which should be able to cover the analysis: GS-CarbonPLOT, HP-PLOT Molsieve, HP-PLOT Q and HP-PLOT U. There are similar types f. ex from Supelco.

As I learned from the discussion until now, the detection of O2 in N2 will be rather difficult. I told this to ADC and they said, its possible to use CO2 as matrix for the O2 permeation.

Thank You for Your help
Florian

Florian,

Maybe I have not fully understood your sample requirements. Is your sample oxygen in nitrogen matrix OR carbon dioxide in nitrogen matrix. I have been under the understanding that both oxygen and carbon dioxide are present at the same time in the matrix. It is not difficult to separate oxygen from nitrogen.

Gasman

Hello Gasman,

Originally the request is to analyse CO2 AND O2 in N2 as matrix. But if there are problems with resolving O2 from the matrix N2 I could do two different analyses instead: CO2 in N2-matrix and O2 in CO2-matrix.
Carrier gas in all cases should be helium.

Florian

Emsman,

I am not sure why you think you still need an inlet if you are going to be buying a valve for injections. Flow control yes, split/splitless inlet no. Also, I bet you that the TCD is the most expensive option but if you are dealing with high levels probably the best option as well.

Best regards.

Florian,
I work with permanent gases for a long time, and I would suggest you to use a porous polymer(like Hayesep D 100/120 10' at 50 Celcius or porapak Q...) at 30cc/min helium carrier gas for the CO2 in pure N2. You will be able to get rid of the N2 before the elution of CO2 which is the last one of permanent gases to elute.
For the O2 in N2, a Molecular Sieve 5A 60/80 8' at 50 Celcius at 30cc/min with helium carrier flow will be perfect.

I will suggest to use 2 channels to measure those 2 impurities in pure N2. One 6 ports injection valve with one porous polymer column for the CO2. One backflush valve with a Mol sieve 5A for the O2. The backflush config is used to get rid of the N2 quicker. However, you can also use a simple injection valve for this channel too.

You can work with a HID.

I will personnaly work with a PED since I have one that can get really good LDL as low as 1ppb for your impurities. The HID can't be reliable at this level!!
Let me know if you want more details, I already have configured a lot of system like you requested in past.

regards
dany