Are sub-2 μm particles best for separating small molecules? An alternative

Abstract

Superficially porous particles (SPP) in the 2.5–2.7μm range provide almost the same efficiency and resolution of sub-2μm totally porous particles (TPP), but at one-half to one-third of the operating pressure. The advantage of SPP has led to the introduction of sub-2μm SPP as a natural extension of this technology. While short columns of both SPP and TPP sub-2μm particles allow very fast separations, the efficiency advantages of these very small particles often are not realized nor sufficient to overcome some of the practical limitations and disadvantages of such small particles. Advantages and disadvantages of columns packed with sub-2μm particles are described for comparison with the characteristics of larger particles. The authors conclude that while sub-2μm particles have utility in research studies, columns of larger particles are often better suited for most applications. A suggested 2.0μm superficially porous particle diameter retains many of the advantages of sub-2μm particles, but minimizes some of the disadvantages. The characteristics of these new 2.0μm SPP are described in studies comparing some present sub-2μm SPP commercial columns for efficiency, column bed homogeneity and stability.