In recent years, high purity silicas bonded with monofunctional C18 and fully end capped have become the standard phase for difficult analyses. The success of this approach is evidenced by the large number of these phases available. They do have some drawbacks: these being primarily tailing with some bases at neutral pH and a high degree of similarity in selectivity. Despite these drawbacks, such phases are popular and we have produced such a phase on Exsil Pure.