As  you don't  know the composition of the rubber septum so you have to be sure about that the septum itself does not produce any volatile chemicals.My suggestion  is that use silicon rubber replacing the odinary rubber .

You can use grey rubber septa (halobutyl septa, like the comercial pheromone ones), but remember to add a treatment control with clean grey septa only to consider the possible effect over the moth. Also remember to clean the septa prior use, with a solvent like hexane or dichloromethane.

Thank you.

My point of this question is to know if the release rate is important in the wind tunnel.

(I don't know the release rate from this dispenser)

Maybe you should get/produce a release kinetics curve first. Without it, you have no way of knowing, if your experimentation does not work, if it is because of the used blend or because of the release rate... 

Release rate is important because if the rate change the amount of total volatile also change as a result the attraction or replancy also change .i.e. 1ml/min and 1ml/30 sec is not same amount of volatiles pushing in the wind tunnel.

Fanny Barsics & Abhishek Mukherjee:

Thanks,

How can I determine the release rate from a grey rubber septum? Which method is the best?

you can measure flow rate of the septum by any flow meter and an adjust the flow rate accordingly

Are you sure?!

Which flow? I put the lure solution (volatile collection in hexane) in the septum, then allow hexane to evaporate and the dispenser dry. I want to know the release rate from this dried dispenser. I think this does not has flow to determine.

This is my method, do you have a different way?

Still I could not understand your method very well but I can give an idea to measure it from your given condition.You can observe the time it takes to disappear all the dried lure from your dispenser then you can get the rate of the volatile release.

Thanks a lot Abhishek

This would be helpful.