pulsed splitless injection

[cay1000]

Hi,

How high pressure can go up for pulsed splitless injection (agilent)?
My solvent is always water, so I could not inject high volume.
I want to apply pulsed splitless injection method to increase the injection volume.
However, is it too much to increase the press 90psi for 2 min in order to inject 2uL (solvent-water)?
The inlet volume is 900uL, but the column is DB-Wax 30m X 250um X 0.5um.

Help me!!

Best regards,

Kelly

[willnatalie]

the max pressure is 100 psi. 90 is really high, but not the max.

[cay1000]

the max pressure is 100 psi. 90 is really high, but not the max.

which means that I can try but sounds like not a realistic way?

Thanks~ Willnatalie

[Don_Hilton]

It is worth trying - and keep in mind that at sufficient pressure the water will condense if the inlet is not hot enough.

Water has never been my favorite solvent in a GC. Is there a way you can exchange the sample into a different solvent or use SMPE?

[chromatographer1]

You NEVER, EVER, want to have water as liquid phase on a fused silica column, no matter what the bonded phase you have may be.

If you might describe the analyte you wish to measure, the one that is dissolved in the water, a whole universe of options might be opened for you from the members of the forum.

SPME, headspace, sample prep options, and who knows how many other options might be available for you.

Or ...................

you can destroy an expensive column needlessly.

Your choice. Choose well.

Rod

[CE Instruments]

At almost all costs avoid injecting water
Water expands a lot on evaporation and pressurising the injector is not going to help enough. In splitless operation I doubt that you can even go to 1ul without contamination of the inlet lines on the injector. You run the risk of carry over and worse destroying the pneumatics if water get back to them.

As suggested above , headspace , SPME , CLSA, P & T solvent extraction, anything to avoid water injections.

[Bigbear]

I agree with most of the replies. I did have to use water in a recent trouble shooting, and was only able to inject 0.5ul. My injection pressure was ~ 20 psi @ 125C. I use a single gooseneck liner.
If you have to use water Agilent has a 150 psi EPC.

[cay1000]

Thanks, all!!

I should not inject water that much to prevent expensive parts for GC.
I will keep that in mind.

I tried SPME method, but the intensity was too weak to analyze ethyl carbamate.

The one of journals I found says the injection volume is 2uL of the solvent containing 40% alcohol.

Thanks!!