These publications describe the traditional chromatographic silica as a heterogeneous, acidic surface. The practical result of these developments is columns that are more stable, more reproducible, and produce much better peak shapes. This improved silica often is called Type B silica. Most column manufacturers make a Type B silica column, so check with your favorite column supplier for the one you should use. Type A phases and start every new method development project with a Type B phase.
Smaller particles produce columns with higher plate numbers as well as higher back pressure.
Higher flow rates mean shorter run times, and as the saying goes, time is money. These columns use less solvent, but during the method development stage they place unnecessary demands on the LC system, such as requiring smaller sample volumes and minimizing extracolumn plumbing and detector cell sizes. My preference for using any of these short or narrow diameter columns is to wait until the fine-tuning stage at the end of method development. Another choice that can have a bearing on the success of the separation is the organic solvent. Each solvent has unique selectivity advantages, but chromatographers seldom can predict which solvent will be the best choice on this basis.