inject air/moisture sensitive samples

Discussions about GC and other "gas phase" separation techniques.

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Hello,

I am working with a lot extremely air/moisture sensitive chemicals for assay or concentration analysis. Samples were prepared in a glove box and then manual injected into the GC.

To minimize the decomposition, I am seeking a way that will prevent samples from exposing to air during the injection, such as setup a transferline for injecting sample in the glove box, or install a encloser to a autosampler, then purge the system with inert gas........

Injecting this type of chemicals, syringes were found very problemetic too. After few times use, it will already cause severe sample decomposition (I rinsed the syringes with dried solvents before and after injection). Not to mention they die quickly due to the clogging.

Does anyone has any experiences with injecting/handling this type of chemicals? Or any suggestions on building a air/moisutre free system to transfer the samples from vials to GC inlet?

Any help would be greatly appreciated!

QQIB

QQIB,

How volatile are your compounds of interest?

Best regards.

Since they are liquids, you could try using a LSV (liquid sample valve). These are normally used to inject samples that are liquid under pressure. The valve is installed in the carrier line upstream of the inlet. You'd then plumb up tubing (usually 1/16") from your glove box to the valve and back. You could then force the samples through the valve using a syringe or whatever other system you come up with. Look at Valco's web sitehttp://www.vici.com/vval/gc_int.php for the valves.

AICMM wrote:
QQIB,

How volatile are your compounds of interest?

Best regards.



Thanks for asking, AICMM :)

I would say that most of my compounds are semi-volatiles, some are pretty volatile. The vapor pressure of these compounds varies from low of 1 Torr@120C to high of 100 Torr@85C....

Another thing that may be worth mentioning is that some of the compounds are organometallics.

Thanks again and have a good week!

QQIB,

I would argue a PLIS injector is probably the way to go. I thought about the LSV that larkl suggests but if your sample is not volatile, it will not flash well enough (if at all) to get good results. PLIS is a heated, groove in plunger, injector made by a Canadian company that could very well work for your application. I will try to get a web site address or contact info for you to take a look.


Best regards.

larkl wrote:
Since they are liquids, you could try using a LSV (liquid sample valve). These are normally used to inject samples that are liquid under pressure. The valve is installed in the carrier line upstream of the inlet. You'd then plumb up tubing (usually 1/16") from your glove box to the valve and back. You could then force the samples through the valve using a syringe or whatever other system you come up with. Look at Valco's web sitehttp://www.vici.com/vval/gc_int.php for the valves.



Larkl,

Thank you so much for the suggestion.

I don't have any experience with the sampling valves, it looks a little bit complicated to me. I will consult VICI for more technique support. Looks like a whole set of the sampling system would cost somewhere between 1000 to 2000 dollars, wow.

Have a good week!!

Sincerely,

QQIB

AICMM wrote:
QQIB,

I would argue a PLIS injector is probably the way to go. I thought about the LSV that larkl suggests but if your sample is not volatile, it will not flash well enough (if at all) to get good results. PLIS is a heated, groove in plunger, injector made by a Canadian company that could very well work for your application. I will try to get a web site address or contact info for you to take a look.


Best regards.



AICMM,

The PLIS you have suggested looks very interesting!

I did a google search with "PLIS", and I was able to find the canadian company named Transcendent Enterprises Inc. and their product PLIS/HPLIS. They also have a online manual:
http://www.transcendent.ca/images/HPLIS_Manual.pdf

If I understood it right, a pressurized sample cylinder or canister will be connected to the PLIS sample chamber for introducing samples. This device will not expose samples to air/moisture at any time, nor requires a syringe, should work very well for my needs.

One thing I am not sure about is the Air Pressure Actuator. Does this mean air will enter into the sample chamber? Or the air will go to a different path?

I am grateful for your help.

Sincerely,

QQIB

QQIB,

Sorry for the delayed response. The air actuator used in the PLIS valve does not interact with your compounds of interest, it is in a separate chamber.

Did you get this issue resolved?

Best regards.
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