Chromatography Forum

Not sure im asking this in the right spot, if it is not, I can make another thread.

I am creating butane standards for a headspace GC method. I am wondering if I take my stock butane solution 1000ug/mL and dilute it down to 100ug/mL. Then move 50uL of the 100ug/mL standard into a 20mL headspace vial, will the concentration still be 100ug/mL? Or do I need to take the volume of the headspace vial into account?

Thanks,
D

If you treat your sample the same as the standard ie putting 50 uL of sample into a 20 mL headspace vial, then you can base your results on the standard being 100 ug/mL. you do not have to take into account the volume of the headspace vial.

Just curious, how do you make a 1000 ug/mL butane standard? What is the solvent?

Dave

Not sure im asking this in the right spot, if it is not, I can make another thread.

I am creating butane standards for a headspace GC method. I am wondering if I take my stock butane solution 1000ug/mL and dilute it down to 100ug/mL. Then move 50uL of the 100ug/mL standard into a 20mL headspace vial, will the concentration still be 100ug/mL? Or do I need to take the volume of the headspace vial into account?

Thanks,
D

I would be interested in how you think that moving a solution from one vial to another can affect its concentration. Unless you are concerned about partition into the headspace, which is exactly what you need in order to do the analysis.

Peter

If you treat your sample the same as the standard ie putting 50 uL of sample into a 20 mL headspace vial, then you can base your results on the standard being 100 ug/mL. you do not have to take into account the volume of the headspace vial.

Just curious, how do you make a 1000 ug/mL butane standard? What is the solvent?

Dave

In a lot of volatiles analysis you make stock standards of permanent gasses by filling a gas tight syringe with the gas then either bubbling it into a partially filled volumetric flask that has methanol in it that is on a balance until you get the desired change in mass. You can also just flow the gas above the solvent and watch the increase in mass without bubbling, both ways are often used.

If analyzing butane by FID it would probably be better to use carbon disulfide as the solvent since it would elute later and have a much lower response.

Personally I prefer to just purchase pre-made high concentration solutions.