Thank you for the information. However, the PFB is not so volatile gas and diffuses slowly. We can heat up the sample to liberate the dissolved PFB to occupy the headspace, but we can not be sure if the concentration thus obtained could be very accurate.
I would thank you again for suggesting the method. If we can get some method to calculate dissolved gas concentration in the aqueous/or any other media for PFB, that will be great.