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

Importance of the topic

Analysis of per- and polyfluoroalkyl substances (PFAS) and cyanotoxins in water is critical for protecting public health and the environment. PFAS are persistent pollutants widely used in industrial and consumer products, while cyanotoxins produced by harmful algal blooms pose acute risks to drinking water supplies. Robust analytical protocols following EPA 537.1, 544, and 545 ensure accurate monitoring, regulatory compliance, and rapid response to contamination events.

Objectives and Summary of the Study

This study demonstrates the application of a single LC–MS/MS platform with automated method switching to perform simultaneous PFAS (EPA 537.1) and cyanotoxin (EPA 544 and 545) analyses. Key aims were to:

• Establish validated calibration curves with R² > 0.99 across target analytes.
• Evaluate system robustness, accuracy (80–120%), and precision (<15% RSD) at LLOQ, mid, and HLOQ levels.
• Assess a rapid five-minute rinse procedure to prevent cross‐contamination between methods.
• Demonstrate continuous high-throughput operation over 54 hours (294 injections).

Methodology and Instrumentation

Samples were analyzed on a Shimadzu LCMS-8060RX triple quadrupole mass spectrometer equipped with an autosampler and column switching valve. Method switching allowed:

• EPA 537.1 path: Delay column (Shim-pack Velox SP-C18, 2.7 µm, 2.1×50 mm) to remove PFAS background.
• EPA 544/545 path: Direct flow path bypassing the delay column to analyze cylindrospermopsin and anatoxin-a.

Chromatographic conditions for each method included Shim-pack GIST C18 or Velox SP-C18 columns at 40–45 °C, flow rates of 0.25–0.3 mL/min, and run times of 8–18 minutes. Electrospray ionization in positive or negative mode, with optimized gas flows and temperatures, ensured sensitive detection. A five-minute rinse with appropriate mobile phase was performed between methods to prevent carryover.

Main Results and Discussion

Continuing calibration checks after sequential triplicate injections showed:

• Linearity: R² > 0.99 for all analytes under EPA 537.1, 544, and 545.
• Accuracy: 80–120% at LLOQ, mid, and HLOQ concentrations.
• Precision: RSD < 15% across calibration levels.
• Carryover control: Five-minute rinse maintained stable LOQ accuracy and precision after method switching.
• System reliability: 294 injections over 54 hours demonstrated workflow robustness without performance degradation.

Chromatograms of PFBS (PFAS) and cylindrospermopsin (cyanotoxin) at LOQ levels confirmed consistent peak shape and signal intensity before and after switching.

Benefits and Practical Applications

Integrating PFAS and cyanotoxin methods on a single LC–MS/MS system offers:

• Reduced instrumentation footprint and capital expenditure.
• Minimized analyst intervention and manual method changes.
• High throughput for routine water quality monitoring.
• Rapid response capability for emerging contamination events like harmful algal blooms.

Future Trends and Possibilities

Advances to consider include:

• Integration of high-resolution mass spectrometry for non-target screening of unknown contaminants.
• Automated data processing and AI-driven quality control to accelerate result validation.
• Portable field deployable LC–MS systems for on-site monitoring.
• Expansion to additional regulatory methods and emerging analyte classes.

Conclusion

A single Shimadzu LCMS-8060RX platform with automated method switching efficiently supports EPA 537.1, 544, and 545 protocols. The approach delivers accurate, precise, and high-throughput analysis of PFAS and cyanotoxins in water. A brief rinse step effectively prevents cross‐contamination, streamlining workflow and reducing costs.

References

No formal literature references were provided in the source text.

Instrument Used

Shimadzu LCMS-8060RX triple quadrupole mass spectrometer with Shim-pack Velox SP-C18 and Shim-pack GIST C18 columns, delay column, autosampler, ESI source.