Rapid Determination of Sulfur Hexafluoride in Enviornmental Air by Gas Chromatography Coupled with Valve Switching for Removing Oxygen and Air Resistance for Stabilizing Airstream

A method was established to rapid quantitatively analyze SF₆ by gas chromatography (GC) with micro-cell electron capture detector. A gas sample was inducted to GC by a ten-port valve. Two 5Å molecular sieve columns with same specification were used for separating and analyzing respectively. Chromatographic baseline fluctuation was eliminated by stabilizing airstream with air resistance and matching the front air pressure of separating column and analytical column. Gas chromatographic analysis rate of SF₆ was improved by removing oxygen through valve switching. The results showed that, under the optimzed experimental conditions, the analysis time of a single gas sample was 1.0 min, and linear relationship was found between peak height and volume ratio of SF₆ within 1.51×10^-12-4.97×10^-8L·L^-1, with detection limit (3S/N) ) of 1.30×10^-12L·L^-1, and the lower limit of determination (10S/N) of 4.80×10^-12L·L^-1. The enviornmental air samples were analyzed 10 times by the proposed method, and the relative standard deviation of the determination results of SF₆ was 0.61%.