Dr. Christopher Higgins

Professor, Civil and Environmental Engineering, Colorado School of Mines

The challenges

Finding a tool that:

Enables comprehensive detection of poly- and perfluoroalkyl substances (PFAS)
Delivers compound-specific information, such as fragmentation information for structural elucidation of unknown species
Facilitates the identification of a broad suite of PFAS

The solution

We used a mixed mode liquid chromatography (LC) separation with high-resolution mass spectrometry and data-independent fragmentation. We first applied polar phase separation chemistry, which we switched out depending on our anionic, cationic or zwitterionic targets, and then a non-polar phase (typically a C18 phase) for analytical separation.

A quadrupole time-of-flight (QTOF) mass spectrometer allows simultaneous:

Targeted analysis: Quantification with standards and mass labeled surrogates available
Suspect screening: Semi- quantification of suspect compounds (previously identified compounds without reference standards)
"True" non-target analysis: Identification of novel compounds and candidate structures from accurate mass and fragmentation information

The outcomes

LC-QTOF-MS/MS provides a means to investigate novel or previously uncharacterized PFAS, while simultaneously performing targeted and suspect screening analyses
Suspect screening identified 167 PFAS from 37 classes in soils and soil effluents from aqueous film-forming foams (AFFF)

“One of the things we like about the SCIEX X500R QTOF system is that it allows us to simultaneously target and quantify compounds when we have standards and mass labels surrogates available. It also can do suspect screening, which is a lot of what we do. We deal with previously identified compounds without reference standards. More importantly, the X500R System has the ability to go back and do what I call “true” nontargeted analysis — where we’re really just saying we don’t have any idea what this compound is.”

Type of organization

Colorado School of Mines is an educational institution and research organization.

Goals

Detect and analyze PFAS in environmental samples.

Applications

Application of high-resolution mass spectrometry to environmental analysis of PFAS