headspace vial question

[duantech]

When to use 20 mL and when to use 10 mL? What's the ads and cons from each kine? What the level range of the liquid in each kind of vials?

thanks

duantech

[chromatographer1]

Good questions.

When testing for analytes that have a high volatility from the matrix in which you are testing and you wish to measure very low levels, use a larger vial and a large sample and a larger equilibrium time.

If you want to achieve a faster equilibrium use a smaller sample and a smaller vial.

If you have semi volatile analytes use a much smaller sample and a smaller vial for faster equilibrium and lower levels of detection for the semi-volatile analytes.

If the levels you want to measure are large, 1% or even more, use a very small sample in a large vial.

I hope this makes sense.

In general, using a smaller sample or a smaller vial means the time required to achieve equilibration is reduced.

Use a larger vial only when low levels of volatile analytes are measured from a large sample, or when large impurities are measured from a small sample.

The only time I wanted or needed to use a 20mL vial is when I measured benzene in water at less than 1 ppb with a GC-HS FID. I used a 15mL sample of water.

best wishes,

Rod