Tony Taylor is the technical director of Crawford Scientific and ChromAcademy. He comes from a pharmaceutical background and has many years research and development experience in small molecule analysis and bioanalysis using LC, GC, and hyphenated MS techniques. Taylor is actively involved in method development within the analytical services laboratory at Crawford Scientific and continues to research in LC-MS and GC-MS methods for structural characterization. As the technical director of the CHROMacademy, Taylor has spent the past 12 years as a trainer and developing online education materials in analytical chemistry techniques.
Much has been written about options for increasing efficiency in HPLC ? primarily through the use of core shell and sub 2 ?m particles, which have been used to increase efficiency, speed up separations or increase peak capacity. However, many separations can only be effectively improved, by optimising selectivity ? resolution is a function of selectivity, efficiency and retention, with selectivity being the most effective at achieving good resolution.
Why would one want to use a mobile phase containing 100% water? Usually to wash the analyte or old mobile phase from the column (stationary phase surface) or to help retain analytes which elute quickly using mobile phases containing only very small amounts of organic solvent (usually highly polar analytes).