title: Production and Transport of Gaseous18F-Synthons:18F-Acyl Fluorides.
abstract: Fluorine-18 (18F, T1/2=109.7 min) is a positron-emitting isotope that has found extensive application as a radiolabel for positron emission tomography (PET). Although gaseous11C-CO2and11C-CH4are practically transported from cyclotron to radiochemistry processes,18F-fluoride is routinely transported in aqueous solution because it is commonly produced by proton irradiation of18O-enriched water. In most cases, subsequent dry-down steps are necessary to prepare reactive18F-fluoride for radiofluorination. In this work, a simple module was designed to generate gaseous18F-acyl fluorides from aqueous18F-fluoride solution by solid phase18F-radiofluorination of acyl anhydride. The gaseous18F-acyl fluorides were purified through a column containing Porapak Q/Na2SO4, resulting in high yields (>86%), purities (>99%) and specific activities (>1200 GBq/μmol). Prototypic18F-acetyl fluoride (18F-AcF) was readily transported through 15 m of 0.8 mm ID polypropylene tubing with low (0.64 ± 0.12 %) adsorption to the tubing. Following dissolution of18F-AcF in solvent containing base, highly reactive18F-flouride was generated immediately and used directly for18F-labeling reactions. These data indicate that18F-acyl fluorides represent a new paradigm for preparation and transport of anhydrous, reactive18F-fluoride for radiofluorinations.
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55901, USA.
authors.forename: Huailei
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, University of Nebraska-Lincoln, 818C Hamilton Hall, Lincoln, NE 68588, USA. sdimagno1@unl.edu.
authors.forename: Stephen G
authors.initials: SG
authors.lastname: DiMagno
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First St. SW, Rochester, MN 55901, USA.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: DeGrado
keywords: 18F-fluorination; Fluorine-18; acyl fluoride; positron emission tomography; radiochemistry; radiofluorination