Routine High Resolution Mass Spectrometry (HRMS) for the Screening of Per- and Polyfluoroalkyl Substances (PFAS) Using the Waters ACQUITY™ RDa™ Mass Detector

This technical brief highlights a targeted workflow for routine HRMS screening using the ACQUITY RDa Mass Detector with UNIFI™ software for PFAS analysis. To demonstrate this a standard mix of thirty-three known PFAS and PFAS precursors were analyzed at a concentration of 10 ng/mL.

Combining the ACQUITY RDa with the UNIFI screening workflow, identification and characterization of the sample components and the associated fragments generated, were carried out automatically using libraries within the processing method. All components were detected and identified with mass measurements less than or equal to 3.2 ppm accuracy without the need for manual interpretation. This demonstrates a platform capable of providing robust PFAS screening and characterization for a wide range of analytical expertise.

Benefits

• Routine acquisition of sub 5 ppm mass accuracy for PFAS compounds
• Simultaneous acquisition of fragmentation data for additional confidence in compound identification 
• Accurate mass screening workflow with waters_connect™ enables automatic screening of PFAS libraries for simplified data analysis
• In Silico generation and visualization of fragment data for increased confidence in PFAS assignment
• Automatic setup and calibration with no manual intervention required
• Access to HRMS data for non-expert users
• Compliant ready software UNIFI software as part of the waters_connect informatics platform

PFASs are a group of diverse chemicals that are widely used in industry to produce fluoropolymer coatings and products resistant to heat, stains, grease, and water. The wide range of applicability of these compounds has resulted in ubiquity throughout a multitude of commercial and industrial processes.

However, these same properties also confer characteristics that are non-biodegradable, result in bioaccumulation in soil and aquatic life, contaminate groundwater, and surface water while also being linked to negative effects on human health.^1,2

With increasing regulation around the monitoring and characterization of PFAS and associated precursors and intermediates, the need for access to instrumentation that provides the necessary selectivity to confidently identify these compounds has grown.³ HRMS provides compound characterization capability, but can be expensive and require high levels of expertise to operate and for data interpretation. With the ACQUITY RDa Mass Detector (Figure 1), HRMS analysis is accessible to both experts and non-experts alike, with automatic set-up and calibration requiring no manual optimization. In combination with the compliant ready UNIFI screening application within the waters_connect™ software platform this provides a robust, easy to adopt route to routine accurate mass measurements for PFAS analysis with minimal MS expertise required.

The ACQUITY RDa Detector was set up automatically, including detector, auto-tune, and mass calibration with no requirement for manual intervention enabling the analyst to focus solely on sample analysis and result generation. Following this routine set up, full scan accurate mass data were acquired in negative mode incorporating the ‘Scheduled Lockmass’ function to mitigate any potential mass accuracy shifts due to laboratory environment changes such as temperature changes. This feature runs a lockmass correction once per hour providing stable mass accuracy with a significant reduction in lockmass solution usage.

A 10 ng/mL sample of the standard solution was injected using the ACQUITY Premier System coupled to the ACQUITY RDa System with all 33 compounds being successfully detected and identified using a PFAS screening library as part of the UNIFI processing method (Figure 2).

All compounds were detected and identified with mass accuracy measurements ranging between -2.9 and 3.2 ppm, providing high confidence in correct compound assignments, with lowest levels of quantitation (LLOQ’s) ranging between 1.0 pg/mL and 9.18 ng/mL (Table 1).

Using the Full Scan with Fragmentation function allows cone voltage ramping to simultaneously acquire high and low energy spectra. The high energy data function, containing fragment ion information, was assigned automatically providing further confidence for compound identification with visual assignations to aid in speedy data appraisal (Figure 3).

The ACQUITY RDa has demonstrated the ability to detect and identify all the components of the screening standard. All compounds were identified with mass accuracy measurements of less than or equal to 3.2 ppm. Creation of PFAS libraries allows for routine screening of samples using accurate mass, fragments, and retention times for confident component identification significantly reducing analyst burden for data interpretation. With the ACQUITY RDa and UNIFI as part of waters_connect providing simple intuitive workflows, HRMS measurements for PFAS are achievable for novice users and ms experts alike.

1. Current Review of Increasing Animal Health Threat of Per- and Polyfluoroalkyl Substances (PFAS): Harms, Limitations, and Alternatives to Manage Their Toxicity. Peritore FA, Gugliandolo E, Cuzzocrea S, Crupi, Rosalia, Britti, D; Int. J. Mol. Sci. 2023, 24(14), 11707. https://doi.org/10.3390/ijms241411707

2. Directive (EU) 2020/2184 of the European Parliament and of the Council of 16 December 2020 on the Quality of Water Intended for Human Consumption (Recast) [Online]. https://eur-lex.europa.eu/eli/dir/2020/2184/oj

3. Total Oxidizable Precursor (TOP) Assay- Best Practices, Capabilities and Limitations for PFAS Site Investigation and Remediation”. Ateia M., Chiang D, Cashman M., and Acheson C. Environmental Science and Technology. https://pubs.acs.org/action/showCitFormatsdoi=10.1021/acs.estlett.3c00061&ref=pdf