Why You Should be Using a Delay Column for PFAS Analysis

PFAS in the Environment Today

Poly- and perfluoroalkyl substances (PFAS) are rapidly emerging as some of the most important environmental contaminants to monitor around the world. Known as “forever chemicals”, their widespread use and persistence make them a truly global issue. PFAS regulations continue to get stricter, which is just another reason scientists need to ensure that their PFAS analyses are accurate and reproducible.

Eliminating the impact of PFAS in the LC System

PFAS analyses are commonly performed by LCMS. And, as any good scientist knows, avoiding contamination is crucial to achieve accurate results. But this can be difficult with PFAS in particular because many components of LC systems contain per- and poly-fluorinated alkyl substances. While measures can be taken to reduce PFAS background interference and contamination, some parts of your LC system may still contain PFAS.

This is where a delay column comes into play. The delay column is added into the mobile phase flow path immediately before the injector, which catches the background PFAS before they reach the analytical column (see figure 1 below). When the sample is injected, only PFAS in the sample will focus at the head of the analytical column. Then, during the gradient analysis, PFAS from the sample will move through the column like normal. The background PFAS trapped in the delay column during equilibration will be eluted and pass through the analytical column as well, but later than the sample PFAS since it entered the system after the injected sample due to additional retention of the delay column.

Eliminating PFAS Contamination of the Sample

One more important factor to consider when eliminating contamination affecting results is the sample container. When storing and injecting the sample, it is extremely important to ensure that the vial is not a source of contamination. Use a PTFE-free vial, cap, and septa such as our PTFE-free snap seal vial and corresponding PTFE-free closure.

If you have any questions regarding your analytical PFAS testing, reach out to one of our technical product specialists today at support@chromtech.com.