With the onset of porous polymer packings, a number of remarkable separations have evolved, unencumbered by the excessive tailing and bleeding taken as a way of life with the substrate loaded packings. This paper describes the use of one of these packings, Porapak Q, in a novel dual column arrangement using one detector. The detector is a homemade thermistor block with a small dead volume. Both sides of the detector are used alternately as reference and sensing sides. The gas mixture passing through the “hot” column separates the CO2, H2S, and SO2 from the remaining gases, while the “cold” column separates the A, O2, N2, and CO. The analysis is relatively fast (17 minutes) and has been in routine use for some months.