STATIONARY PHASES FOR POROUS LAYER OPEN TUBULAR COLUMNS
Thomas J. Bruno, Paris D. Svoronos Cambanas
The practical application of solid adsorbents in capillary chromatography typically makes use of porous layer open tubular (PLOT) columns. Early capillary PLOT columns suffered from detector spiking due to particulates becoming dislodged and entering the detector. This was resolved by placing a short length of a polymeric column (usually polydimethuyl siloxane) as a particle trap before the detector, however recent advanced in manufacturing methods have resulted in nearly complete binding of particles on the inside of the column. In this table, several of the more common PLOT column stationary phases are listed, along with the separations that may be affected and some additional information. The maximum temperatures listed represent the point of severe resolution loss. The materials are often chemically stable to much higher temperatures. The user should also be aware that the adsorption of water during use will often change retention characteristics dramatically, sometimes resulting in a reversal of positions of adjacent peaks. This can result from traces of water in the carrier gas. Due to surface adsorption of solutes, some experimentation with temperature may be necessary to prevent tailing or to avoid statistical correlation (or a propagating error) among replicate analyses.