GAS-CHROMATOGRAPHY OF TITANS ATMOSPHERE .5. DETERMINATION OF PERMANENT GASES IN THE PRESENCE OF HYDROCARBONS AND NITRILES WITH A MOLECULAR-SIEVE MICROPACKED COLUMN AND OPTIMIZATION OF THE GC PARAMETERS USING A DOEHLERT EXPERIMENTAL-DESIGN

An alternative for the GC determination of permanent gases in Titan's atmosphere, given the severe constraints of space instrumentation, is the use of a 100-120-mesh molecular sieve 5A micropacked column. Because of its high efficiency, small pressure drop and short analysis time, such a column is fully compatible with the experimental constraints of the Cassini-Huygens mission. In order to optimize the GC conditions associated with this column, a methodological approach was supported by a Doehlert experimental design. With such optimized conditions, the column provides a rapid separation of the selected products under isothermal conditions, with about 900 theoretical plates per metre at 70 degrees C for most of the solutes studied.