FTIR and GC as complementary tools for analysis of corrosive gases

The gas metrology laboratory of the National Metrology Institute of South Africa has developed methodology for the gravimetric preparation of corrosive gas mixtures such as nitric oxide (NO) in nitrogen, as well as sulphur dioxide (SO₂) in nitrogen or synthetic air. Fourier transform infrared (FTIR) spectroscopy has been used to analyse for trace and ultra trace levels of infrared active gaseous species, such as NO, nitrogen dioxide and SO₂ that are difficult to analyse by other means. These corrosive gas mixtures are also analysed using gas chromatography with pulsed helium ionisation detection to complement the work done using FTIR with infrared active impurities. A comparison between the techniques of FTIR, gas chromatography and non-dispersive infrared spectroscopy for corrosive gas analysis is also presented.