SummaryThere has been much effort spent in recent years developing the technology for free radical crosslinking of polysiloxane polymers to prepare capillary columns coated with thermally stable and nonextractable stationary phases. Organic peroxides have been used extensively as the free radical initiators for the in situ polymerization of the stationary phases. However, these peroxides adversely affect the phase polarity and column activity. Seven azo compounds were studied for crosslinking efficiency. Azo compounds can be used as free radical initiators to prepare nonextractable stationary phases without the adverse effects caused by peroxides.

A crosslinkable biphenylmethylpolysiloxane stationary phase was synthesized for capillary column gas chromatography and compared with methyl, phenyl, and cyanopropyl polysiloxane stationary phases for the separation of isomeric polycyclic aromatic compounds. While the new phase gave similar separations of nonpolar isomers when compared to the nonpolar phases, separations of polar isomers were greatly improved because of the induced polarity of the biphenyl group of the stationary phase by the solute molecules. This polarizable stationary phase offers a unique selectivity which is not available in other stationary phases.

No abstract

this work was from the U.S. Department of Energy, Contract No. DE-FG02-86ER60445. This work was also supported in part by the Gas Research Institute, Contract No. 5084-260-1129, and by Finnigan-MAT. Any opinions, findings, conclusions, or recommendations expressed herein are those of the authors and do not necessarily reflect the views of DOE, GRI, or Finnigan-MAT.

SummaryInstrumentation was assembled that allows the use of supercritical ammonia as mobile phase in capillary supercritical fluid chromatography. Several modifications of the typical chromatographic system were necessary, especially with respect to injection and detection. In addition, the stabilities of various polysiloxane stationary phases were studied. The chromatography of polarizable and polar basic materials was demonstrated using a nonpolar polysiloxane stationary phase.