Articles & Tech Notes

What’s So Special About TFA? TFA (Trifluoroacetic acid) has several properties that make it very important that you take the right precautions when evaporating it, in order to get optimum performance and prevent damage. Firstly, it’s an acid. This means that if not handled with care, it will corrode components of a system over time. Next, it is quite volatile (with a boiling point / pressure characteristic pretty similar to methanol). In combination with other solvents it can present a quite “bump-prone” mixture Thirdly, (and perhaps most infamously), it exhibits “creep”. In simple terms, this means that liquid TFA can climb the sides of a vessel to the height that any TFA vapour reaches. What is more, it can carry with it dissolved compounds, which may then end up actually leaving the vessel. Fourthly, and particularly worryingly for users who run into this problem, it can seep through polypropylene (including some brands of 96 well microtitre plates). This is not evidence of a failure to seal the bottom of the well during moulding of the plate – it actually goes through the plastic itself, due to it having an extremely low surface tension. TFA in sufficient concentration will also attack silicone (both silicone rubber seals and the special oil in a standard Genevac Cole pump). Finally, it can soften a PTFE coating on an item that is exposed to liquid TFA for any great length of time.