The molecular imaging technique of positron emission tomography (PET) is an increasingly important tool in biomedical research and in drug discovery and development. Many small molecule drugs and potential PET radiotracers carry trifluoromethyl (CF₃) groups. Because CF₃ groups are generally considered to be metabolically stable, there is a strong interest in developing drugs with these groups. This invention describes a novel method and apparatus for producing no-carrier added [¹¹C]fluoroalkanes, which can be used as labeling agents for PET radiotracers at CF₃ groups. Prior to this technology, no method for [¹¹C]fluoroalkyaltion has existed. The reported method, which involves passing [¹¹C]methane over a heated column of a metal fluoride, has high yield and high specificity, is simple, fast, and capable of being fully automated. Of special interest is the efficient production of [¹¹C]fluoroform, which can be readily applied to labeling a variety of chemotypes with a [¹¹C]trifluoromethyl group.