Single-System LC-MS/MS for PFAS and Cyanotoxin Detection: Method Evaluation and Mobile Phase Additive Influences

Per- and polyfluoroalkyl substances (PFAS) and cyanotoxins are recognized contaminants of concern in drinking and surface waters. In response to regulatory requirements and potential emergency events, laboratories increasingly seek efficient analytical strategies for monitoring both classes of compounds. EPA Methods 537.1 (PFAS), 544 (microcystins and nodularin), and 545 (cylindrospermopsin and anatoxin-a) all employ LC-MS/MS, indicating that a single instrument capable of supporting these methods could enhance laboratory efficiency and reduce operational costs. This study presents an approach for the quantitative analysis of PFAS and cyanotoxins using a single triple quadrupole mass spectrometer while maintaining analytical accuracy and sensitivity.

Eighteen PFAS (Method 537.1), six microcystins, nodularin (Method 544), cylindrospermopsin, and anatoxin-a (Method 545) were measured on a Shimadzu LCMS-8060RX. PFAS were separated in 18 minutes using a Shim-pack Velox SP-C18 column, while cyanotoxins were analyzed in 8 minutes using a Shim-pack GIST C18 column (Method 545) and a Velox SP-C18 column (Method 544). Since PFAS are analyzed in negative ion mode, prior exposure of the system to acidic mobile phases required for cyanotoxin detection can result in ion suppression, especially detrimental for the required trace detection of these compounds. System robustness was demonstrated by continuing calibration checks, which confirmed that sensitivity and selectivity were maintained across methods with an appropriate rinsing protocol. Results from this extended evaluation, including calibration linearity, accuracy, and reproducibility over time, will be presented.

This presentation demonstrates increased LCMS and workflow efficiency for the environmental testing lab.