New nitrophenyl- and nitromethoxyphenyl-substituted methylpolysiloxane stationary phases for capillary column gas chromatography

✍ Scribed by Zoltan Juvancz; Michael A. Pulsipher; Michelle M. Schirmer; R. Scott Johnson; Karin E. Markides; Jerald S. Bradshaw; Milton L. Lee

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 768 KB
• Volume: 1
• Category: Article
• ISSN: 1040-7685
• DOI: 10.1002/mcs.1220010610

✦ Synopsis

Nitrophenyl-, nitrophenylethyl-, dinitrophenylethyl-, and methoxynitrophenylethyl-substituted polysiloxanes (2S-S0% substitution) have been synthesized and evaluated as stationary phases in capillary column gas chromatography. Phases with 25% substitution and with ethylene spacers between the phenyl substituents and the polysiloxane backbone were found to provide high efficiencies, moderate thermal stabilities, and useful selectivities. Without flexible hydrocarbon spacers, the stationary phases exhibited poor efficiencies. The 50% substituted phases generally provided narrower operational temperature ranges and lower efficiencies, and they were more difficult to immobilize by free radical crosslinking. Several methods of immobilization were evaluated, and a dynamic procedure with dicumylperoxide (DCP) was found to produce the best results for these nitrophenyl-containing phases. The enhancements in polarity resulting from the resonances of the nitrophenyl substituent groups provided unique selectivities for specific applications involving aromatic compounds. The dinitrophenyl-containing phases showed, in addition, selectivity based on charge transfer complex formation.