Application of Valve Switch Technique in Fast Analysis of SF_6 in Atmospheric Samples(In Chinese)

A GC-ECD method for fast analysis of trace SF_6 in atmospheric samples was established with valve switch technique.The sample was passed through the fore-cut column,a 3.2 mm×1 m OD stainless steel tube packed with 40/60 mesh 5A M.S.,0.6 minutes later,switching 6-port valves simultaneously,the components having larger retention values was discharged out of the analysis system,only SF_6 passing through the analyzing column,a 3.2 mm×0.5 m OD stainless steel tube packed with 60/80 mesh 5A M.S.,and ECD.Under the experimental chromatographic conditions,the average peak-height response of SF_6 was 1.08×10~~(-14)mL/μV,with the average relatively standard deviation of 2.2%,and the limit of detection of SF_6 was 6.03×10~(-13)mL(triple baseline noise).The sample analyzing time was 1.2 min.It was much shorter than nor- mal analysis method.Eleven atmospheric samples were analyzed in 12 minutes with the average relatively standard deviation of 2.1%.

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