Overview
Detecting PFAS presents unique analytical challenges due to the large number of compounds (over 12,000 identified), their varying properties, and the need for ultra-trace detection in complex matrices. Multiple analytical approaches have been developed to address different aspects of PFAS analysis.
Targeted Analysis (LC-MS/MS)
The most common approach uses liquid chromatography coupled with tandem mass spectrometry to detect and quantify specific, known PFAS compounds. This method is highly sensitive and selective.
Advantages
- High sensitivity (ng/L levels)
- Quantitative results
- Well-established protocols
- Regulatory acceptance
Limitations
- Only detects known compounds
- Requires reference standards
- Typically 20-40 compounds
- Misses PFAS precursors
Total Oxidizable Precursor (TOP) Assay
The TOP assay converts PFAS precursor compounds into terminal perfluoroalkyl acids through oxidation, revealing the "hidden" PFAS burden in a sample. This method was a key research focus of PERFORCE3.
Advantages
- Captures precursor compounds
- Better total PFAS estimate
- Identifies transformation potential
Limitations
- Not fully standardized
- Incomplete conversion
- More complex procedure
Total Fluorine Methods
Methods like Combustion Ion Chromatography (CIC) and Particle-Induced Gamma-ray Emission (PIGE) measure total organofluorine content, providing an upper bound for PFAS contamination.
Advantages
- Captures all organofluorine
- No standards needed
- Fast screening tool
Limitations
- No compound identification
- Includes non-PFAS fluorine
- Less sensitive
Non-Target Screening (HRMS)
High-resolution mass spectrometry enables discovery of unknown PFAS compounds through characteristic fragmentation patterns and mass defect filtering.
Advantages
- Discovers new compounds
- Retrospective analysis
- Structural information
Limitations
- Complex data processing
- Semi-quantitative only
- Requires expertise