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PFAS testing is entering a new phase. With seven ultrashort-chain organofluorine compounds included in EPA Method 563, drinking water laboratories face a new set of analytical challenges, from poor chromatographic retention and background contamination to limited fragmentation.
Designed specifically for these emerging requirements, EPA Method 563 uses LC-MS/MS to determine seven ultrashort-chain PFAS in drinking water: TFA, TFMS, PFPrA, PFMOAA, PFEtS, PFPrS and TFSI.
New technical note
See how the SCIEX QTRAP 6500+ system provides a practical LC-MS/MS workflow for meeting the analytical requirements of EPA Method 563.
Why ultrashort-chain PFAS are different
Ultrashort-chain PFAS bring challenges that laboratories may not encounter to the same extent with conventional PFAS workflows.
Their high polarity and low hydrophobicity can make chromatographic retention difficult. Their low molecular weights can contribute to elevated background noise and limit fragmentation options for MS/MS detection. Compounds such as TFA and PFPrA can also be present in laboratory solvents, reagents and consumables, making background contamination an important consideration.
These challenges make robust chromatography, sensitivity and contamination management particularly important when implementing EPA Method 563.
A faster workflow for EPA Method 563
The new SCIEX technical note demonstrates a direct injection LC-MS/MS workflow on the QTRAP 6500+ system for all seven compounds included in the method.
Using a Phenomenex Luna Omega PS C18 analytical column, the optimized workflow achieves good retention and peak shape for highly polar analytes while reducing the chromatographic gradient from 28 minutes in EPA Method 563 to 10 minutes, a 64% reduction in run time.
For laboratories preparing for higher sample volumes, that shorter analysis time offers the potential to significantly increase throughput while maintaining the chromatographic performance required by the method.
Performance designed around UCMR 6 requirements
The workflow was evaluated for sensitivity, accuracy, precision and robustness against the analytical criteria in EPA Method 563.
Most notably, verified lowest concentration minimum reporting levels (LCMRLs) were below the proposed UCMR 6 minimum reporting levels for six of the seven target compounds.
Low ng/L sensitivity was demonstrated for several challenging compounds, including:
- PFPrS: 3.68 ng/L
- PFEtS: 5.14 ng/L
- TFMS: 6.44 ng/L
The workflow also demonstrated stable performance across an extended analytical sequence, with internal standard recoveries of 57–149% across approximately 150 injections over 24 hours, remaining within the EPA Method 563 acceptance range.
Putting the method to the test with real drinking water
The SCIEX workflow was also applied to a variety of drinking water samples, including tap, filtered, bottled and reverse-osmosis water.
TFA was the most frequently detected ultrashort-chain PFAS in the samples evaluated, with concentrations ranging from below the LCMRL up to 1,312 ng/L.
When a representative drinking water matrix was fortified and analyzed in replicate, recoveries ranged from 76.6% to 103%, with %RSD values from 2% to 13%, demonstrating reliable quantitation across the target analyte panel.
Be ready for the next step in PFAS monitoring
The introduction of EPA Method 563 marks an important development for laboratories involved in drinking water PFAS analysis.
With seven ultrashort-chain PFAS bringing new chromatographic, sensitivity and contamination challenges, laboratories need workflows built around the specific demands of these analytes.
The SCIEX workflow combines a 10-minute gradient, direct-injection LC-MS/MS analysis, verified reporting levels and automated calculations in SCIEX OS software to provide a practical approach for laboratories looking to implement EPA Method 563.
See the full method performance
Explore the chromatography, reporting limits, drinking water results and method performance in the complete SCIEX technical note.
Author
Kendra Adams, Simon Roberts & Holly Lee
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