Improved sampling valve for gas chromatography

Backflushing and Two-Stage Operation of Capillary Columns in Gas Chromatography.

“…A small laboratory oven was added for thermostatting a gas sampling valve and a carrier gas flow switching valve at 80" C. Both valves were the same type: a pneumatically operated diaphragm valve (Type D) obtained from the Greenbrier Plant of the Bendix Corp. Leak-free service was obtained by polishing the internal surfaces of these valves (6).…”

“…A commercial version of the latter valve has been satisfactorily used by the author for gas sampling (6). This valve is also .used in the present work for backflushing and two-stage operation of capillary columns.…”

“…Only data on a few of the lighter paraffins were compared, since with the valve the heavier paraffins were backflushed, and without the valve they were temperature-programmed (6).…”

“…Gustafsson, Sundman. and Lindh (6) determined the area of spots of carbohydrates from densitometric measurements on film on which the images appeared brignt on a dark background. Sulser ( I S ) employed circular paper chromatography to separate fatty acids and to detect adulteration of rape seed oil.…”

“…Crum (2) and Wall (10) have described slider-type valves, and Karasek and Ayers (4) have described a unique diaphragm-type valve. A commercial version of the flatter valve has been satisfactorily used by the author for gas sampling (6). This valve is also used in the present work for backflushing and two-stage operation of capillary columns.…”