Like FSPE, Fluorous High Performance Liquid Chromatography (FHPLC) utilizes fluorous silica, packed as an HPLC column, as the fluorous phase to extract fluorous molecules. Fluorous HPLC, however, goes beyond FSPE and separates fluorous molecules from other fluorous molecules based on fluorous content. Fluorous molecules can be differentiated from each other by the length of the fluorous chain or the number of fluorous chains. The more fluorine atoms present, the greater the retention time of the fluorous HPLC column.
The separation of fluorous molecules from each other can sometimes be accomplished by standard chromatographic techniques, including traditional or reverse phase chromatography. However, the best way to separate fluorous compounds from each other is usually by chromatography over FluoroFlash® fluorous silica.
FluoroFlash® HPLC columns are packed with a proprietary fluorous silica gel specifically designed for HPLC applications. Under F-HPLC conditions, FluoroFlash® silica gel separates compounds primarily based on fluorine content while compound polarity plays a minor secondary role. This allows for the separation of fluorous compounds based on size of the fluorous tag and is the basis of fluorous mixture synthesis (FMS) where mixtures are deconvoluted using F-HPLC. FluoroFlash® HPLC columns are available in range of sizes from analytical to semi-preparative. Please consult the F-HPLC application note for more details.
An illustrative example of F-HPLC deconvolution is shown below with a family of fluoroacyl-tagged amides. The control compound lacking the fluorous tag (C7H15) comes off with the solvent front, as do most other non-fluorinated organic compounds under these conditions. The fluorinated homologs then emerge strictly in order of fluorine content, and a solvent gradient is needed to push the more highly fluorinated members of the series off the column.