9. 32 x 11,6 mm. screw neck vial with inner cone. 0,3 mL. 11. 32 x 11,6 mm. snap ring vial with inner cone. In order to optimally dissolve both short- and long-chain PFAS in the vessels, the sample solution should have a relative proportion of methanol of 40 - 60 %. Also, for reliable PFAS analysis fluorine-free septa are required to prevent