Optimizing Large Volume Injections to Achieve Ultra-Low Level Detection while Maintaining Method Robustness

Polyfluoroalkyl Substances (PFAS) in the Environment
Oral Presentation

Prepared by E. Parry, D. Weil, T. Anumol
Agilent Technologies, 2850 Centerville Rd, Wilmington, DE, 19808, United States


Contact Information: [email protected]; 302-358-7390

ABSTRACT

Per and polyfluorinated alkyl substances (PFAS) are a group of man-made compounds that are ubiquitous in environment. Possible adverse effects to humans and animals have made them a public health concern. In June 2022, the USEPA issued interim drinking water health advisory limits (HALs) for PFOA at 0.004 ng/L, PFOS at 0.02 ng/L, GenX at 10 ng/L and PFBS at 2,000 ng/L to reduce risk to the public from exposure to these PFAS. Different strategies to achieve part per quadrillion sensitivity are available. For example, a larger sample volume can be extracted to increase the concentration factor, however, this strategy is time consuming and laborious. Increasing the injection volume is an easier and more efficient approach as it allows a great improvement in sensitivity by loading more analyte mass onto the LC/TQ. Large volume injection of high organic content (e.g., 80% methanol for drinking water) on reverse phase column can cause poor chromatographic peak shapes thus decreasing sensitivity if the appropriate steps are not taken. Techniques to address broadening peak shape include selection of different analytical column phase and dimensions, usage of pre-column focusing cartridges, sandwich injection and post injection mixing. While these techniques can be effective, they also introduce method limitations such as limited maximum LC back pressure, column lifetime reduction and background introduction. Approaches for implementing these techniques while maintaining the robustness which is the key in routine tests will be presented.