FLUID-INCLUSION VOLATILE ANALYSIS BY GAS-CHROMATOGRAPHY - APPLICATIONOF A WIDE-BORE POROUS-POLYMER CAPILLARY COLUMN TO THE SEPARATION OF ORGANIC AND INORGANIC-COMPOUNDS

Gas chromatographic analyses of the volatile content of fluid inclusio ns were carried out using a recently developed PoraPLOT(R) Q mega-bore capillary column (25 m x 0.53 mm, 20 mu m film thickness, fused silic a) and on-line crushing techniques during heating. For comparison, ana lyses were also conducted with a HayeSep(R) R packed column (10' x 1/8 '' 120 mesh, Ni alloy tubing), which is the column most widely used f or the analysis of inclusion gases. The wide-bore PoraPLOT(R) Q capill ary column is ideally suited for analyses at relatively high flow-rate s needed in processing fluid-inclusion gases released into the gas chr omatograph by on-line crushing. This column proved superior to the pac ked column in that it reduced retention times by at least half, allowe d clean separation of N-2, CO2, CH4, and higher hydrocarbons up to at least C-6 paraffins, and greatly improved detection and accuracy of an alyses for H2O. Furthermore, using N-2 as a carrier gas, it is possibl e to analyze for Ar and H-2 to similar to 10(4) mu moles and similar t o 10(-5) mu moles, respectively. The latter gas could not be analyzed with the packed column. Optimum conditions were found to be a carrier- gas flow of 20 mL/min, and an oven temperature programmed to start at -20 degrees C, subsequently raised (10 degrees C/min) to 35 degrees C and held for 10 min, then again raised (5 degrees C/min) to 115 degree s C. Runs lasted similar to 80 min. The PoraPLOT(R) Q capillary column was used to measure the composition of carbonic fluid inclusions in t he peralkaline granite at Strange Lake, Quebec-Labrador. These inclusi ons were shown to contain heavy aliphatic hydrocarbons in proportions consistent with their production via a Fischer-Tropsch reaction involv ing Fe-oxide-catalyzed hydrogenation of magmatic CO2 and CO.