Gas chromatography in space.

Gas chromatography has proven to be a very useful analytical technique for in situ analysis of extraterrestrial environments as demonstrated by its successful operation on spacecraft missions to Mars and Venus. The technique is also one of the six scientific instruments aboard the Huygens probe to explore Titan's atmosphere and surface. A review of gas chromatography in previous space missions and some recent developments in the current environment of fiscal constraints and payload size limitations are presented.

Improvement of Gas Chromatographic Performance of Cyclic Siloxane Bonded Phases by Incorporation of n-Alkyl Groups.

Cyclic siloxane-based silica columns of high retention capacity for light hydrocarbons were prepared by incorporation of octyl and octadecyl groups on the siloxane skeleton. Spectroscopic studies revealed the presence of the alkyl groups on the silica surface, which results in high surface coverage of the packing materials. The retention characteristics of the columns are significantly higher than those of cyclic siloxane phases due to their high surface coverage and better solute-stationary phase interactions. In agreement with previous data for micropacked columns, the H vs u curves, on passing through the optimum region, remained substantially constant at high linear gas velocities, indicating their usefulness for fast analysis of light hydrocarbons at high flow rates without any appreciable loss in column performance. Presumably due to greater availability of the bonded alkyl groups for interactions, a 10-component mixture of C(1)-C(4) saturated and unsaturated hydrocarbons was sufficiently separated on the hexamethylcyclotrisiloxane-octadecylsilyl phase compared to the conventional octadecyldimethylsilyl phase, irrespective of the high carbon content of the latter.