[18F]Fluoride recovery via gaseous [18F]HF

Acidification of target water with H₂SO₄ in a specially constructed glassy carbon/polyethylene apparatus allowed for recovery of up to 82% of ¹⁸F]fluoride as ¹⁸F]HF gas. The ¹⁸F]HF distillate was found to be acid‐free but moist; when passed through a solution of ^tBuPh₂SiOTf, it yielded ¹⁸F]^tBuPh₂SiF. The multivariate design of experiment showed that the key to high yield of ¹⁸F]HF was the efficient degassing of the reaction mixture.