Best Analytical Methods for Testing PFAS: An Evaluation of Current Techniques

January 10, 2025

by Birch Biotech

Per- and polyfluoroalkyl substances (PFAS) have become a major environmental concern due to their persistence and potential health risks. As awareness grows, so does the need for accurate testing methods to detect PFAS in various environmental samples, including water, soil, or air.

The EPA industry-standard methods for testing PFAS use liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This technique offers high sensitivity and specificity, allowing for the detection of PFAS at very low concentrations. EPA Method 537.1 is widely used for drinking water analysis, while modified versions are applied to other matrices.

Proper sampling techniques can establish accurate results for monitoring PFAS. You'll need to avoid using materials containing PFAS during sample collection and handling. Low-flow sampling methods are often preferred for groundwater to minimize disturbance and ensure representative results. As analytical capabilities improve, alternative methods are being developed to address a broader range of PFAS compounds and environmental matrices.

Understanding PFAS and Their Significance

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals with widespread uses and environmental impacts. These compounds have unique properties that make them persistent in the environment and potentially harmful to human health:

PFAS are synthetic chemicals characterized by their strong carbon-fluorine bonds. This structure gives them unique properties like water and oil repellency, heat resistance, and chemical stability.
PFAS include thousands of different compounds, with perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) being two of the most well-known.
Their stability makes PFAS extremely persistent in the environment, earning them the nickname "forever chemicals."

Sources and Routes of Contamination

PFAS contamination stems from various industrial and consumer products. Major sources include:

Firefighting foams
Non-stick cookware
Water-resistant textiles
Food packaging
Industrial processes

PFAS can enter the environment through:

Direct release from manufacturing facilities
Use of PFAS-containing products
Disposal of PFAS-contaminated materials

These chemicals can contaminate soil, water, and air. PFAS can spread through different environmental media, making them difficult to contain and remove once released.

PFAS and Public Health Concerns

The widespread presence of PFAS in the environment raises significant public health concerns. Exposure to PFAS can occur through:

Drinking contaminated water
Consuming food with PFAS
Using products containing PFAS

Health effects associated with PFAS exposure include:

Increased cholesterol levels
Changes in liver enzymes
Increased risk of certain cancers
Effects on the immune system
Thyroid hormone disruption

The persistence of PFAS in the human body adds to these concerns, as these chemicals can accumulate over time. Ongoing research continues to uncover potential long-term health impacts, emphasizing the need for effective detection and removal methods.

Sampling Strategies for PFAS

Proper techniques for accurately testing PFAS minimize contamination risks and ensure representative results across various environmental media. PFAS sampling research focuses on developing standardized protocols to address the unique challenges of these persistent compounds. You should follow strict guidelines to prevent sample contamination:

Avoid using materials containing PFAS, such as Teflon-coated equipment or water-resistant clothing. Instead, opt for PFAS-free sampling gear and personal protective equipment.
Implement a field quality control program, including equipment blanks and field reagent blanks, to identify potential sources of contamination. This helps ensure the integrity of your samples and validates your results.
When collecting PFAS samples, use polypropylene or high-density polyethylene containers. Rinse these containers with PFAS-free water before use to remove any potential contaminants.
Store samples at temperatures below 10°C and analyze them within 14 days to maintain sample integrity. Avoid contact with aluminum foil, as it may contain PFAS.
Use low-flow sampling techniques for groundwater to minimize turbidity and ensure representative samples. This method reduces drawdown and purge volumes.

Types of Environmental Samples

PFAS sampling encompasses various environmental media:

Drinking water: Collect samples directly from the tap after flushing the system.
Surface water: Use grab samples to capture specific moments or composite samples to evaluate conditions across time, location, or media mixtures, depending on the study objectives.
Groundwater: Employ low-flow sampling techniques or passive diffusion samplers.
Soil: Collect samples using stainless steel equipment and store them in HDPE containers.
Landfill leachate: Use specialized techniques depending on the complexity of the sample matrix.

Consider the potential impacts of runoff and stormwater conveyance systems when selecting sampling locations. This ensures you capture a comprehensive picture of PFAS distribution in the environment.

Analytical Methods for PFAS Detection

Accurate detection and quantification of PFAS require sophisticated analytical techniques. Several established and emerging methods enable precise measurement of these persistent compounds in various environmental matrices.

EPA Methods and Standard Procedures

The EPA has developed standardized methods for PFAS analysis in different media. EPA Method 537.1 is widely used for testing drinking water and can detect 18 PFAS compounds at levels as low as parts per trillion. For air emissions, the EPA introduced the Other Test Method (OTM)-50; this method measures 30 volatile PFAS from stationary sources using passivated stainless-steel canisters.

ASTM D8421 and D8535 provide definitive procedures for analyzing PFAS in aqueous and solid samples respectively. These methods employ liquid chromatography/tandem mass spectrometry (LC/MS/MS) with optional isotope dilution to minimize matrix interference as mentioned in EPA 537.1.

High-Resolution Mass Spectrometry

High-resolution mass spectrometry (HRMS) offers superior selectivity and sensitivity for PFAS detection. This technique can identify both known and unknown PFAS compounds in complex environmental samples. HRMS instruments like quadrupole time-of-flight (QTOF) or Orbitrap analyzers provide accurate mass measurements.

HRMS enables non-targeted analysis to discover novel PFAS. It can detect a broader range of compounds compared to traditional targeted methods. The high mass accuracy helps distinguish PFAS from interfering substances in challenging matrices like soil or wastewater.

Liquid Chromatography Techniques

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is the gold standard for PFAS analysis: this method separates PFAS compounds chromatographically before detection by mass spectrometry. LC-MS/MS can achieve ultra-low detection limits in the parts per trillion range.

Key advantages of LC-MS/MS include:

Multi-compound analysis in a single run
High specificity and sensitivity
Ability to quantify branched and linear PFAS isomers

Ultra-high performance liquid chromatography (UHPLC) improves separation efficiency through the use of smaller stationary-phase particle sizes and higher pressures. This technology enables faster analysis times while maintaining high resolution, offering improved separation of closely eluting PFAS compounds with optimized conditions.

Data Quality and Method Development

Reliable PFAS analysis requires robust analytical methods and careful attention to data quality. Achieving low detection limits while minimizing interferences is crucial for accurate PFAS quantification in complex environmental matrices.

Development of Analytical Methods

PFAS analytical methods development focuses on improving sensitivity, selectivity, and reliability. High-resolution mass spectrometry enables the identification of both known and unknown PFAS compounds. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is widely used for targeted PFAS analysis.

Method development steps include:

Optimizing chromatographic separation
Refining ionization and fragmentation parameters
Validating calibration procedures
Determining method detection and quantitation limits

Ongoing research aims to expand the range of detectable PFAS and lower detection limits. Multi-laboratory validation studies help ensure methods produce consistent results across different labs and analysts.

Setting Data Quality Objectives

Establishing clear data quality objectives (DQOs) is essential for meaningful PFAS analysis. DQOs define the required level of data quality to support project decisions. Key considerations for PFAS DQOs include:

Required detection and quantitation limits
Acceptable precision and accuracy
Sample preservation and holding times
Quality control sample frequency and criteria

Be sure to tailor your DQOs to your specific project needs and regulatory requirements. Clearly defined DQOs guide method selection, sampling procedures, and data evaluation.

Addressing Matrix Effects and Interferences

Complex sample matrices can interfere with PFAS analysis, leading to inaccurate results. Addressing matrix effects is vital for reliable results. Common approaches include:

Using isotopically labeled internal standards
Optimizing sample cleanup and extraction procedures
Applying matrix-matched calibration
Employing standard addition techniques

It is important to carefully evaluate potential interferences from co-eluting compounds, as well as the effects of ionization suppression, which can reduce signal intensity and compromise detection sensitivity. Method modifications may be necessary for challenging matrices like biosolids or landfill leachate.

Rigorous quality control measures help identify and mitigate matrix effects. These include analyzing method blanks, matrix spikes, and certified reference materials.

Advancements in PFAS Testing

Recent breakthroughs in PFAS analytical methods development have significantly improved detection capabilities and efficiency around background contamination. Innovative technologies, optimized methods, and alternative approaches are transforming how you can analyze these PFAS species.

Innovative Technologies

New analytical methods are pushing the boundaries of PFAS detection. High-resolution mass spectrometry now allows you to identify previously unknown PFAS compounds with remarkable accuracy. Nano-materials and biosensors offer rapid, on-site testing options. These tools can detect PFAS in water samples within minutes, providing real-time data for immediate decision-making.

Advanced software algorithms enhance data interpretation, enabling you to process complex PFAS mixtures more efficiently. Machine learning techniques are improving the identification of PFAS analogs and their transformation products.

Best analytical methods of testing for PFAS

Refinements to liquid chromatography-tandem mass spectrometry techniques have lowered detection limits. Now it is possible to measure PFAS at parts per trillion levels in various environmental matrices.

Improved sample preparation methods reduce matrix interferences, enhancing accuracy. Solid-phase extraction techniques have been optimized for different PFAS classes, allowing for more comprehensive analysis.

Automated systems streamline workflows, increasing throughput and reducing human error. You can now process more sampling research in less time while maintaining high data quality.

Validation of Alternative Approaches

Non-targeted screening methods are gaining traction for PFAS analysis. These approaches allow you to identify a broader range of PFAS compounds without pre-selecting target analytes.

Total organic fluorine (TOF) analysis provides a cost-effective way to estimate total PFAS content. While not compound-specific, TOF offers a useful screening tool for contaminated sites.

Passive sampling techniques are being validated for long-term PFAS monitoring. These methods can capture time-weighted average concentrations, giving you a more comprehensive picture of PFAS exposure over time.

Regulatory Criteria and Reporting

PFAS regulations focus on water safety and environmental protection. Regulatory bodies have established criteria for PFAS levels and reporting requirements, which is important for compliance and effective PFAS testing.

Water and Environmental Regulations

The EPA has set health advisory levels for PFAS in drinking water: for PFOA, the level is 0.004 parts per trillion (ppt), while for PFOS it's 0.02 ppt. These levels are significantly lower than previous standards. GenX chemicals have a final health advisory level of 10 ppt. PFBS has a higher limit at 2,000 ppt.

State regulations may vary and can be more stringent than federal guidelines, so it is best to check your local regulations for specific requirements.

Reporting and Compliance

Reporting PFAS test results accurately is essential for regulatory compliance. Method blanks are required for every batch of up to 20 field samples. Each analyte must be less than half the method reporting limit. Sample duplicates are recommended for every 20 field samples or fewer. This helps ensure data quality and reliability. When reporting to the method detection limit (MDL), you must qualify detections in the blank between the MDL and method reporting limit.

Regulatory Implications for Testing

Analytical methods for PFAS must meet increasingly stringent regulatory criteria. EPA Method 1633 and ASTM D7979 are commonly used for targeted PFAS testing, with minimum reporting levels around 1 part per billion.

For potable water, you need highly sensitive methods due to the extremely low health advisory levels. Your chosen method must be capable of detecting PFAS at these ultra-low concentrations in drinking water samples.

Non-targeted PFAS testing can identify unknown compounds using high-resolution LC/MS. However, this approach has limitations in quantification and sensitivity.

Interpreting Data and Communicating Results

Effective interpretation and communication of PFAS testing results are crucial for informed decision-making. You'll need to analyze data statistically, use appropriate tools, and convey findings clearly to stakeholders.

Statistical Analysis and Data Presentation

Statistical analysis helps you determine PFAS concentrations accurately:

Calculate basic statistics like mean, median, and standard deviation for each target analyte.
Create visual representations of your data using graphs and charts: bar charts can compare concentrations across different samples, while scatter plots may reveal trends over time or space.
Consider using box plots to display the range and distribution of PFAS levels. This can be particularly useful when you have multiple samples collected from various locations.
Check for outliers, examine the data distribution, and make conclusions.

Use of Data Management Tools

This spreadsheet provided by the Alaska Department of Environmental Conservation is a versatile tool for organizing sampling protocols and analyzing PFAS data:

Set up columns for sample IDs, collection dates, and concentrations of each target analyte.
Use built-in functions to perform calculations and create pivot tables for quick summaries.
Employ conditional formatting to highlight values exceeding regulatory limits.
For larger datasets, consider using specialized environmental data management software.

These tools often include features for quality control checks and automated report generation.

Effective Communication of Findings

When presenting results, tailor your message to your audience:

For technical audiences, include detailed methodology and statistical analyses.
For non-technical stakeholders, focus on key findings and their implications.
Use clear, concise language to explain what the data means. Avoid jargon and define any technical terms you must use.
Create a summary table showing PFAS concentrations in each sample compared to relevant standards or guidelines. This allows for quick assessment of potential risks.
Include a brief narrative explaining any data qualifiers or limitations. Discuss the reliability of your results and any areas where further investigation may be needed.

Key Takeaways

LC-MS/MS is the gold standard for PFAS detection in environmental samples
Proper sampling techniques are essential to prevent contamination and ensure accurate results
Ongoing method development aims to improve PFAS testing capabilities across various matrices

Sources for this Article:

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Readers are advised to refer to our product-specific quality data sheets and Certificates of Analysis (COAs) available on our website for detailed information on product specifications. It is essential to handle and store all materials according to the safety guidelines and regulatory requirements applicable to your area.

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Best Analytical Methods for Testing PFAS: An Evaluation of Current Techniques