As with HPLC, capillary GC method development ideally includes screening several different stationary phases (and maybe phase ratios) for most promising selectivity prior to fine tuning other instrument parameters.Unfortunately, automated screening of capillary GC columns is more complicated than in HPLC.Attempts to use rotary stream selection valves to select between installed columns of interest has not been encouraging enough for widespread adoption do to temperature limitations, peak shape distortion, leaks, etc.