MEASUREMENT OF GASES BY A SUPPRESSED CONDUCTOMETRIC CAPILLARY ELECTROPHORESIS SEPARATION SYSTEM

This paper describes the direct measurement of soluble ionogenic atmospheric gases by a suppressed conductometric capillary electrophoresis separation system (SuCCESS). A small circular wire loop is incorporated at the sampling end of a fused silica capillary located immediately at the tip in the same plane as the capillary. When the loop is dipped into a solution and withdrawn, a liquid film is formed on it, The film is in fluid communication with the capillary and acts as a microreservoir. When the film end is lifted relative to the destination side, all or part of the film contents can be injected into the capillary. To perform gas sampling, a series of automated operations are conducted with a commercial CE instrument modified in a minor fashion: the film-bearing loop is lowered into a sample chamber, and air is sampled for a preset period of time at a preselected flow rate (typically 1 min at 100 cm(3)/min), The capillary is then lifted to introduce an aliquot from the film for analysis and then dipped into the running electrolyte source vial, and electrophoresis is commenced. Under the above sampling conditions, 1 ppb SO2 can be detected. The system should be applicable for use with other detection modes and nonaqueous electrolytes.