Residual monomer in Polivinil alcohol

[Margarita]

I am trying to analyse the residual monomer (vinyl acetate) in the polyvinyl alcohol using the headspace. We dissolve the polymer in DMSO with heat and put in the Headspace. We are heating at 120ºC but the peak of the vinyl acetate does not appear, the boiling point to the vinyl acetate is 71-73ºC and we are sure that there is vinyl acetate residual (more or less 20 ppm).
Does anyone know that is happening?

[xxx]

Your problem could have many sources :
-detector sensitivity
-injection problem
-sample preparation

It's not always necessary to dissolve your product in solvent for HS(solution approach).

Where and how do you dissolve the monomer before putting in a HS vial???It looks as if you loose vinyl acetate by heating to dissolve.


Put you monomer with dmso in HS vial direct to prevent losses,and let it disollve at 120°C during incubation.


What are your gc method parameters (column,oven,detector ....)
Have you try with a standard,do you see it,do you see the solvent peak (DMSO)

See you

[chromatographer1]

Have you considered the reactivity of vinyl acetate when heated?

(What will heating vinyl acetate in bulk produce ?)

Try dissolving the polymer without heating in another solvent (toluene?), or test without dissolution as mentioned above, and keep your temperature down.

Vinyl acetate is volatile enough but it may take some time for it to equilibrate at lower temperatures.

Remember if it were easy, anybody could do it.

Good luck.