Theory of fast capillary gas chromatography - Part 4: Column performance vs. liquid film thickness

The negative effect of the liquid stationary phase film thickness on the co lumn efficiency is strongest for peaks with retention factors, k, in the vi cinity of k = 0.3-0.4 and rapidly diminishes with the departure of k from t hat region. Additionally, at the high pressure drop required for fast analy sis of complex mixtures, the negative effect of the same film thickness dim inishes with the increase in column length, regardless of the k values. In practice, it is recommended to ignore the film thickness and optimize the c olumns as thin film ones regardless of their actual film thickness. Account ing for the film thickness results only in a modest improvement in the reso lution for a few affected peaks - those with k = 0.3-0,4. However, this imp rovement comes at the cost of a substantial increase in analysis time, and should be used only as the action of the last resort.