Abstract
A new column that produces excellent results when first installed sometimes undergoes rapid deterioration, resulting in decreased resolution, tailing peaks, and/or a high rate of bleed. High-quality columns are both material- and labor-intensive. Gas scrubbers and purifiers should be used for even high-purity gases. The presence of contaminants in the carrier gas reaching the column testifies to either exhausted (or improperly installed) gas scrubbers and filters; or subsequent contamination of the clean gas by post-filter passage through dirty lines or soiled inlets. Bulk polysiloxanes exposed to high temperatures and/or oxygen undergoes degradation. Dimethyl polysiloxane subjected to program heating in vacuum produces volatile degradation products, primarily the cyclic trimeric oligimer, which is detectable at 343°C and reaches a maximum at 443°C. “Press-fit” connectors, usually of borosilicate glass and sometimes of fused silica, offer convenient low thermal mass fittings, which when properly installed can be highly dependable. These are available as “sized,” or as “universal” fittings.
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