One System, Multiple Solutions: Analysis of PFAS & Cyanotoxins in Water Adhering to EPA 537.1, 544, and 545

Importance of the topic

Monitoring of per- and polyfluoroalkyl substances (PFAS) and cyanotoxins in water is essential due to their persistence, bioaccumulation potential, and adverse health effects. A unified analytical platform streamlines laboratory operations and ensures rapid response to environmental emergencies.

Objectives and Study Overview

This work evaluates a single Shimadzu LCMS-8060RX triple quadrupole mass spectrometer configured for automatic switching between EPA Methods 537.1 (PFAS), 544 (microcystins/nodularin), and 545 (cylindrospermopsin/anatoxin-a). The goal is to maintain regulatory compliance, high sensitivity, and throughput without instrument cross-contamination.

Methodology and Instrumentation

• Sample preparation: Solid-phase extraction for PFAS; preserved water samples for cyanotoxins with sodium bisulfate/ascorbic acid.
• Standard calibration: 25 PFAS (targets, surrogates, internal standards); two cyanotoxins with isotope-labeled internal standards; seven microcystins/nodularin.
• LC configuration: Shimadzu LC-40 series, two column switching valves, delay column (GIST C18) to reduce PFAS background, Velox SP-C18 analytical columns.
• Gradient programs: 18 min for PFAS; 8 min for cyanotoxins.
• MS settings: ESI negative for PFAS, ESI positive for cyanotoxins; optimized gas flows and temperature controls.
• Automation: Five-minute rinse step integrated into batch sequence to prevent carryover between methods.
• Validation design: Triplicate calibrations and continuing calibration checks over 54 h and 294 injections to assess precision, accuracy, and robustness.

Main Results and Discussion

• Chromatographic performance: Baseline separation of 25 PFAS within 18 min; complete resolution of cylindrospermopsin, anatoxin-a, microcystins, and nodularin within 8 min despite some MRM overlap.
• Calibration metrics: PFAS linear from 0.5–50 µg/L (R²>0.99); anatoxin-a 0.02–20 µg/L (R²>0.997); cylindrospermopsin 0.005–10 µg/L (R²>0.999); microcystins/nodularin 0.5–500 µg/L (R²>0.994). Accuracy ranged 80–120%, %RSD<15%.
• Continuing calibration: Stability of accuracy and precision at LLOQ, mid, and HLOQ levels across repeated method switches confirmed system reliability.
• Carryover control: Automated five-minute rinse effectively prevented mobile phase contamination, ensuring consistent data quality.

Benefits and Practical Applications

• Consolidates multiple EPA methods on one instrument, reducing capital and maintenance costs.
• High-throughput capability with minimal downtime supports routine monitoring and emergency response, such as harmful algal bloom events.
• Automation improves reproducibility and lowers manual workload, enhancing laboratory productivity.

Future Trends and Opportunities

Advancements may include expanded multi-method platforms covering additional emerging contaminants, intelligent software for real-time method optimization, and miniaturized systems for field applications to provide rapid on-site analysis.

Conclusion

The single-system approach using Shimadzu LCMS-8060RX with automated method switching delivers accurate, precise quantification of PFAS and cyanotoxins. This efficient workflow reduces instrument redundancy, lowers operational costs, and accelerates environmental and public health decision-making without compromising analytical performance.

Reference

1. EPA Method 537.1: Determination of Selected PFAS in Drinking Water by SPE and LC-MS/MS.
2. EPA Method 545: Determination of Cylindrospermopsin and Anatoxin-a by LC/ESI-MS/MS.
3. EPA Method 544: Determination of Microcystins and Nodularin by SPE and LC-MS/MS.
4. ECHA Progress Update on PFAS Restriction Process.
5. EPA Drinking Water Health Advisories for Cyanotoxins.