Chromatography Forum

Hi All
We use PerkinElmer Clarus 680 with a Turbomatrix 40 for the analysis of transformer gases. Recently we have seen oxygen, nitrogen and carbon dioxide peaks in argon purged vials. (O2 and N2 the ECD and CO2 on FID). The volume of oxygen, nitrogen and carbon dioxide can be anything up to 10ml with no pattern. The system has been checked over by our independent service engineer and a PerkinElmer engineer who all found nothing wrong. Carrier gases have been changed, leak tested etc. but to no avail.

Does anyone know what is causing this and how to fix it ?

Ta Greg

First, I am not a user of Perkin Elmer equipment, but I believe that your problem is common to all suppliers of TOGA analyzers. Basically, it is virtually impossible (in my opinion) to get vials with 0.0 ppm of O2,N2 and CO2. I assume that you are working to the ASTM method D3612 using method C. Look very carefully at table 5, where they give minimum detection limits for the gases. There is a footnote for O2, "Estimated from the H2 response". If you look at your chromatogram, I am sure that oxygen is well separated and the area can be integrated, so why must the response be "Estimated". To me, what they are telling you is that " As we cannot remove the oxygen completely from the vials we need to estimate the response from the hydrogen value".

Here is a bit more evidence. An Italian company, SEA Marconi, have a device to fill the vials with oil in an Argon atmosphere. Type the following into Google, "RT/HS-DGA" and you can download the user manual. If you read through this manual you will see that despite the Argon atmosphere, they advise you to fill a vial with the 'Argon atmosphere' and to subtract the amounts you find for O2 and N2 from your results.

Perhaps somebody can inform me why you need to measure these gases (O2 and N2) as all of the calculations that I have seen to ascertain the condition of a transformer do not include these gases.

Gasman