Need Quantification Method Recommendation

[BOB WILSON]

I have a plastic film that has sesamol as an additive - now the goal is to determine how much is volatilizing into the headspace over time, so quantifying the amount in the gas phase is the goal. What is the best way - in real simple terms? I do have a good internal std canidate.

I'm assuming I would put samples in different vials and sample them over time, or would I sample the same one repeatedly over time?

And what would concentration units be in for headspace....ppm? I know it is not as straight forward as liquid.

Any suggestions would be great....

[Don_Hilton]

not knowing how much is applied, this may or may not be worth consideration. Weigh the film on a very accurate balance at varous times after exposure to the open air. (or eaxposure to a stream of pure nitrogen from a gas cylinder to avoid partitioning with other stuff that would be found in air in the room.)

Exposure to headspace conditions limits you to equilibrium between your sample, the volume of the vial and the sides of the vial.

[Peter Apps]

The equilibrium headspace approach that you suggest will actually slow down the rate of emission from the film because it will increase the gas phase concentration. The simplest approach will be to rig up a purge and cryo-trap device in which the film is continuously purged with nitrogen (or air if oxygen might make a difference) and at appropriate intervals you cryotrap the sesamol coming off and transfer to the GC. The plumbing need not be all that fancy.

Peter