Simultaneous C1–C18 PFAS Analysis in Drinking Water by Large-Volume Direct Injection Using an Altura Poroshell 120 PFAS Column

Significance of Topic

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants frequently detected in drinking water. Ultra-short-chain (USC) PFAS (C1–C3) are especially challenging to analyze due to their high polarity, poor retention on conventional reversed-phase columns, and interference from system-derived background. A robust method capable of simultaneous C1–C18 PFAS determination supports regulatory compliance and protects public health.

Study Objectives and Overview

This work presents a single-injection LC/MS approach for comprehensive C1–C18 PFAS analysis in drinking water. The method employs a newly developed Agilent Altura Poroshell 120 PFAS analytical column paired with a dedicated PFAS delay column and large-volume (up to 100 µL) direct injection of acidified samples. Performance was benchmarked against standard C18 phases, demonstrating improved retention of USC PFAS, reduced contamination, and simplified workflows for routine water testing.

Methodology and Instrumentation

Instrumentation:

• LC: Agilent 1290 Infinity II with PFAS-free conversion kit, 100 µL injection loop, multisampler.
• Delay Column: Agilent Poroshell 120 PFAS (4.6 × 30 mm, 2.7 µm).
• Analytical Column: Agilent Altura Poroshell 120 PFAS (2.1 × 100 mm, 2.7 µm) at 40 °C.
• MS: Agilent 6475 triple quadrupole, negative ESI, dynamic MRM acquisition.

Chromatography:

• Mobile Phase A: 5 mM ammonium acetate + 0.05% acetic acid in water.
• Mobile Phase B: 5 mM ammonium acetate in methanol.
• Gradient: 10% B to 100% B over 14 min, total run ~21 min, flow 0.4 mL/min.

Sample Preparation:

• Filter 50 mL water through 0.2 µm RC membrane.
• Acidify 10 mL aliquot to 0.1% acetic acid; equilibrate 5 min.
• Transfer 0.5 mL to vial, add 10 µL isotopic internal standards, 0.5 mL methanol; vortex.

Calibration and Validation:

• Standards from 1–1000 ng/L in 50:50 methanol/water with 0.1% acetic acid.
• Linearity (R2>0.995), recoveries 80–120% (except DFA), RSD <10%.

Main Results and Discussion

Retention & Peak Shape: Compared with C18 phases, the PFAS column provided clear retention of USC PFAS (TFA, PFPrA) away from the void volume with sharp, symmetric peaks. Delay column integration effectively removed system-derived TFA and PFBA background.

Solvent Effects: Large-volume injections (100 µL) of water:methanol (50:50) showed peak splitting for USC PFAS. Adding 0.1% acetic acid eliminated distortion without raising backpressure.

Full C1–C18 Coverage: A single 15 min gradient on the 100 mm PFAS column achieved baseline separation of 36 PFAS from DFA to PFODA with stable retention and efficiency.

Validation: Calibration curves for 33 analytes (excluding PFODA/PFHxDA low-level inconsistencies) showed excellent linearity. Spiked tap water recoveries ranged 74–109% with RSDs <10%, except DFA (46% recovery) where an isotope-labeled standard is recommended.

Real Samples: Tested bottled, surface, and tap waters. USC PFAS such as PFMeS and PFPrA were detected alongside longer chains, demonstrating method applicability without preconcentration.

Benefits and Practical Use

This workflow enables laboratories to analyze an extended PFAS panel in a single direct injection, avoiding solid‐phase extraction. It reduces system contamination, simplifies sample handling, and maintains compatibility with standard high-pressure LC/MS systems.

Future Trends and Possibilities

As regulations expand to include USC PFAS, demand will increase for methods covering full C1–C18 ranges. Future developments may focus on further contamination control, integration of high-resolution MS, miniaturized sample preparation, and automation for high-throughput screening.

Conclusion

The combination of the Altura Poroshell 120 PFAS analytical column, PFAS delay column, and optimized large-volume injection achieves reliable, simultaneous C1–C18 PFAS analysis in drinking water. This approach offers enhanced retention, reduced background, robust quantitation, and a streamlined workflow for routine environmental monitoring.

References

• PFAS National Primary Drinking Water Regulation. Federal Register (2024).
• D8421-25: Standard Test Method for Determination of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous Matrices by Co-solvation followed by LC/MS/MS. ASTM.
• EUR-LEX - 52024XC04910 - Draft environmental quality standards for PFAS total under the Water Framework Directive. European Commission.
• SCHEER Scientific Opinion on PFAS total under the Water Framework Directive. European Commission, March 2025.
• Zenobio JE, Salawu OA, Han Z, Adeleye AS. Adsorption of PFAS to Containers. Journal of Hazardous Materials Advances. 2022;7:100130.