PFAS LC Column Anatomy: Which Phase, Dimensions, and Particle Type Are Best?

If you work in one of the many labs routinely testing samples for per- and polyfluoroalkyl substances (PFAS), you know that awareness and interest are growing as we continue to better understand the pervasiveness, persistence, and potential health risks associated with these “forever chemicals.” As interest grows, the need for fast, accurate, and precise testing is growing with it. This demand is driving the development of better methods, and LC column selection is the foundation for building an improved approach. Here, we’ll examine the properties that are important to consider when choosing an LC column for PFAS analysis.

Column Phase Selection

The first decision to make when determining which PFAS LC column to use is identifying an effective stationary phase. In our scouting of different phase chemistries for the analysis of short-chain PFAS (C4-C6) and above, the C18 phase proved to be the best choice. As the alkyl chain on PFAS molecules gets longer, the interactions between those chains and the C18 ligand increase, providing a great mechanism for retention and resolution. Retention is strong enough that a relatively short and narrow column can be used to quickly and effectively resolve target analytes. The example in Figure 1 shows that a 50 x 2.1 mm Raptor C18 column easily elutes and separates the compounds of interest while meeting all of EPA 537.1 method criteria for drinking water testing in less than 8 minutes (10 minute total analysis time).