Column packings graphitic carbon

Polymeric Packings. Graphitized carbon or mixed copolymers are used as polymeric packing (e.g., polystyrene-divinylbenzene) or further derivatized with ion-exchange or C4, C8, or C18 functional groups. Columns filled with these packings feature levels of performance comparable to those of silica-based columns and are stable from pH 2 to 13. 

Ciccioh, P. and Liberti, A., Microbore columns packed with graphitized carbon black for high-performance liquid chromatography, J. Chromatogr., 290, 173, 1984. 

Many porous organic polymers are derived from the stationary phase used to pack GC columns. Tenax is one such example. This is a macroporous polymer obtained from diphenyl p-phenylene oxide (DPPO). Generally, this polymer is hydrophobic and does not retain water. However, it exhibits some ability to adsorb polar compounds. As a result of its low surface area (30 m /g), its adsorption capacity is limited and very volatile compounds are not trapped. Therefore, it is an appropriate material for trapping heavier compounds with more than four carbon atoms. Co-precipitated graphitized carbon black and Tenax (in the proportion 23 % to 77 %) was introduced on the market as Tenax GR. This adsorbent combines the advantages of both materials and is approximately twice as effective as Tenax TA [50]. 

Materials with carbon on the surface used as column packings for chromatography include carbosils, which are prepared mainly by pyrolysis of aliphatic alcohols [92], aromatic hydrocarbons [93], chloroalkanes [94], and other organic compounds on the surface of silica gel. The carbon deposit obtained under the standard pyrolysis conditions is amorphous and possesses different physicochemical properties than graphitized carbon blacks. The transformation of such amorphous carbon deposit to graphitized carbon black on a silica gel surface is not possible because of the high temperature of the graphitization process (ca.3000 K). 

H2. Halasz, I., and Horvath, C., Micro beads coated with a porous thin layer as column packing in gas chromatography. Some properties of graphited carbon black as stationary phase. Anal. Chem. 36, 1178-1186 (1964). 

The retention volume has been reported377 for triethyl and tetraethyl silanes on columns packed with silanized Chromosorb W supporting 20% of Apiezon L or 15% of Carbowax 20 M and operated at 120 and 90 °C, respectively, using helium as carrier gas and thermal conductivity or flame ionisation detection. Measurements were also carried out by gas-solid chromatography on columns of Carbochrom-1 (graphitized thermal carbon black with 0.1% of Apiezon L) or Silochrom C-80. 

Thermal desorption Volatile compounds in gases such as pollutants in air can be trapped in a small adsorption tube, either by pumping the gas through or by passive diffusion. The packing in the trap can be chosen from a wide variety of adsorbents (molecular sieves, graphitized carbon blacks, organic polymers). After sample collection the adsorption tube is rapidly heated in a stream of purge gas which transports the released analytes to the GC column where the separation runs. 

Packed column SFC stationary phases are very similar or identical to those used for HPLC. With neat CO2 mobile phases, polymer or polymer-coated silica stationary phases have typically been used. With modified-C02 mobile phases, bonded-phase silica columns are typically used. For structural separations, diol, amino, or cyano stationary phases are most often used. For stereochemical separations, derivatized polysaccharide-bonded sihca columns are most often the stationary phases of choice. A powerful feamre of modified-C02 pSFC is the ability to serially connect different stationary phases to obtain enhanced or multiple mechanism separations. With subcritical (super heated) water mobile phases, the use of polymer, porous graphitic carbon, and polymer-coated zirconia stationary phases has been described. 

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