gas injection

[che313]

regularly 2uL of sample inject in GC - but when we want to inject gas directly how much we have to inject 1ml? 2ml? 5ml?

[chromatographer1]

Most liquids will expand 200 to 2000 times the liquid volume to a gas volume, depending upon the temperatures and pressures involved.

Experiment and see.

Rodney George
consultant

[Consumer Products Guy]

I agree: experiment. Oftentimes we inject 1 ml gas samples.

[larkl]

I'd be very cautious if you're going to apply a liquid external standard calibration to a gas sample. It may not be impossible, but I wouldn't trust the results. Maybe this isn't what you're trying to do.

[Peter Apps]

Ultimately how much you have to inject depends on the concentration (mass:volume) of the sample and the minimum detectable (with acceptable repeatability) quantity (mass) of the detector.

Peter