Capillary action liquid chromatography

Capillary action LC (caLC) is introduced as a technique using capillary action as the driving force to perform LC in capillary columns packed with HPLC type microparticulate materials. A dry packing method with centrifugal force was developed to prepare capillary columns in parallel (10 columns per 3 min) to support their disposable use in caLC. Using a digital microscope for real-time imaging and recording separations of components in a dye mixture, caLC was found to have flow characteristics similar to TLC. Based on the investigation of microparticulate HPLC silica gels of different size (1.5-10 microm) and a typical TLC grade irregular medium, Merck 60G silica, the van Deemter curves suggested molecular diffusion as the major contribution to band broadening in caLC. With Waters Xbridge 2.6 microm silica, plate heights down to 8.8 microm were obtained, comparable to those achievable in HPLC. Assisted by an image-processing method, the visual caLC separation was converted to a classical chromatogram for further data analysis and such a facility confirmed the observation of highly efficient bands.