Analysis of S_2F_10 in decomposed SF_6 by gas chromatography: various aspects

摘要

This paper presents the results of experiments performed to find some practical and simplified chromatographic method for analyzing S_2F_10 in SF_6. A mass detector was used to achieve the necessary sensitivty and to help with the identification of the SF_6 decomposition byproducts. The discussion includes the influence of various instrument parameters and temperature conditions. The use of packed columns (Porapak types) give proper resolution but they induced S_2F_10 decomposition. Bonded-silicon capillary columns were finally chosn for their overall performances. Indeed, the usual gaseous hyproducts (SOF_4, SO_2F_2, SOF_2) can be analyzed and quantify. Also, other heavy SF_6 hyproducts (S_2OF_10, S_2O_2F_10 and other unknowns) have been detected. However, some chemical interactions still take place in the column with the SF_6 hyproducts formed by partial discharges, forming various fluoromethylsilanes. Finally, sensitivity in the tens of ppbv can be obtained with 50 muL injected, while quantification relying on total ion current. (due to the lack of standard S_2F_10 solution) seen to given satisfactory results.