[Determination of impurity components in the perfluoroisobutyrile based on home-made gas-circulating system]

A method for the determination of impurity components in perfluoroisobutyrile (C₄F₇N) gas was established by setting up a sealed pipe gas composition test system comprising an automatic six-way valve and gas chromatography-tandem mass spectrometry (GC-MS) apparatus. C₄F₇N commercial gases were purchased from an abroad company (AC company) and a domestic Chinese company (DC company). These gases were subjected to qualitative and quantitative analyses by our test system and separated on an Agilent GS-GASPRO column (30 m×0.32 mm×5 μm). The results showed that the C₄F₇N commercial gas contained N₂, O₂, C₃HF₇ and a trace amount of C₃F₆. In the C₄F₇N commercial gas from the AC company, the total amount of impurities was 0.13%, and the C₄F₇N content was 99.87%. In the C₄F₇N gas from DC Company, the total amount of impurities was 0.83%, and the C₄F₇N content was 99.17%. The C₄F₇N contents of the gases from both the companies were consistent with the claimed value (≥ 99%). The determination of the impurities C₄F₇N can be beneficial for the subsequent study of its insulation performance and thermal stability.