Stationary phases fluorocarbon

The high thermal and chemical stability of fluorocarbons, combined with their very weak intermolecular interactions, makes them ideal stationary phases for the separation of a wide variety of organic compounds, including both hydrocarbons and fluorine-containing molecules Fluonnated stationary phases include per-fluoroalkanes, fluorocarbon surfactants, poly(chlorotrifluoroethylene), polyfper-fluoroalkyl) ethers, and other functionalized perfluoro compounds The applications of fluonnated compounds as stationary phases in gas-liquid chroma... 

Reta, M., Carr, R W., Sadek, P. C., and Rutan, S. C., Comparative study of hydrocarbon, fluorocarbon and aromatic bonded RP-HPLC stationary phases by linear solvation energy relationships. Anal. Chem., 71, 3484-3496, 1999. 

Formic and acetic acids were determined as the free acids because of high volatility of the methyl acetate and methyl formate and resultant handling losses. Analysis was accomplished with a stationary phase of FFAP (a Carbowax 20M derivative made by Wilkens Instrument and Research, Inc.) on a relatively inert fluorocarbon support. Conditions include ... 

Curran and co-workers have introduced a promising approach to separation and purification procedures by using fluorocarbon-coated solid phases for liquid-phase chromatography. This approach depends on attaching a variety of perfluorocarbon tags to functional compounds which render the eventual substrate mixture separable over the perfluorinated stationary phase [27, 28] (Figure 7.8). 

Adsorption TLC selection of the mobile phase is conditioned by sample and stationary-phase polarities. The following polarity scale is valid for various compound classes in NPTLC in decreasing order of K values carboxylic acids>amides>amines>alcohols>aldehydes > ketones > esthers > nitro compounds > ethers > hal-ogenated compounds > aromatics >olefins > saturated hydrocarbons > fluorocarbons. For example, retention on silica gel is controlled by the number and functional groups present in the sample and their spatial locations. Proton donor/acceptor functional groups show the greatest retention, followed by dipolar molecules, and, finally, nonpolar groups. 

Chromosorb T is a polytetrafluoroethylene (PTFE) support material. It is inert and hydrophobic and therefore suitable for analysis of small polar molecules such as water, organic acids, phenols, amines and acidic gases (HF, HCl, SO2, NO c). Chromosorb T can be coated with stationary phases such as polyethylene glycol, Apiezon or a fluorocarbon oil (Kel-F, Fluoropak-80) but can be difficult to pack. 

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