Chromatography Forum

I am using headspace method for TOGA. Problem: how to purge properly the 20ml vials with argon before filling them with oil?
I am using two syringes for that, one connected to 20psi Ar regulator, other for venting. I am purging 3--5 min and I find air components at high levels. Have anybody any experience on this item?

I am using headspace method for TOGA. Problem: how to purge properly the 20ml vials with argon before filling them with oil?
I am using two syringes for that, one connected to 20psi Ar regulator, other for venting. I am purging 3--5 min and I find air components at high levels. Have anybody any experience on this item?

You may have leaks or the needles are too small that the purging flow is not sufficient.

What volume of argon do you pass through the vial ? - in simple terms every vial volume will cut the air content by 1/2.

With two holes in the septum you will probably get air diffusing in after you have added the oil. For how long do you equilibriate before taking the headspace sample ?

Peter

I would think that this technique is not suitable without extensive cost in Argon gas.

Perhaps filling the vials in an Argon box would be better suited to your needs? At least you should purge the vials without crimping their seals as you purge their environment with Argon. It is a simple test to check the completeness of the evacuation. You could even purge the headspace after filling the vial as long as your results are not in error.

best wishes,

Rod

You might want to look at the site below:

http://www.seamarconi.com/downsm/brochu ... le_eng.pdf

This is an Italian company that makes a device that allows you to fill and cap 20 vials in an atmosphere of Argon.

Gasman

Hi Akar

The method you have described is similar to that listed in transformer DGA standards, such as ASTM D3612 and IEC60567, both good starting points for GC TOGA.

Both actually recommend a lower argon delivery pressure to prevent pressure build up in the vial, but your purging time seems more than sufficient. You haven't mentioned the needle gauges you currently use, and a point already mentioned is that the actually achieved flow may be lower than expected, I also found that non-coring needles did become blocked reducing flow. Plus I found that purging the vials upside down achieved better, more consistent results.

To assess whether the issue is with your purging method or sample introduction method, it may be a sensible idea to test an argon purged vial, and you should expect to see low amounts of O2 and N2 and a very low amount of CO2. Standard IEC60567 states the accepted levels for this test. Also a test to ensure the seal is intact and the top is crimped correctly would be to submerge the vial underwater and check for gas bubbles escaping.

Also have you considered that the oil sample you have testing has a high atmospheric gas content? And as with anything involving a GC your final result is based on a successful accurate calibration.

Hope this helps.

too much air can be remove by transformer oil treatment plants, you may check more info at

http://www.hention.com/portfolio/detail ... ion-plant/