Chromatography Forum

Hi ,
I have a problem in analysis of volatile/light liquid hydrocarbons which have boiling points around 25 - 30 deg C for Detailed Hydrocarbon Analysis with GC.
the problem is that I lose samples before column then get very poor peaks and unrelaiable composition.
I also looked through the applications for this kind of problem.
cooled tray, headspace ( do not if applicable for hydrocarbons because of safety) , cooled injection system, cold on-column injection are some possible solutions.
Is there anyone have experience about this problem and/or these applications ?
and also is there a cooled injector system ? liquid sample evaporates in the injector since it is at room temperature.
thank you.

umitayna,

Light and heavy hydrocarbons or just light? Ending at C9 or something or ending at C44 or something?

Best regards

Hi,

I have problem with the light naphtha type samples that are mainly n-C4, n-C5, i-C5 and less in C3 and C6. these samples are sampled as liquid.

we also analyse the samples which are in the range of C6 - C12 and get good results.

regards.

Get a liquids injection valve like a Valco and inject direct

Get a liquids injection valve like a Valco and inject direct

LSV is an option and in case of LSV use , we need to pressurize the sample in a bomb with an inert gas in order to purge the sample loop. because the liquid itself has not enough pressure at room temperature to travel through the loop.

do you have an experience with auto injection ?

thank you for your comment.

Instead of using a 'bomb' to hold the sample, I would recommend that the sample be contained in a 'syringe cylinder'. These can be purchased from vendors which prepare standards using volatile hydrocarbons as the matrix. You can then have sample flow only when the cylinder valve is opened and the syringe is manually activated to flush the sample valve in the GC before injection.

best wishes,

Rodney George