Targeted analysis is key to precisely detecting and quantifying specific PFAS compounds.
PFAS, known as “forever chemicals,” are difficult to measure. They exist in very low concentrations, often in the parts-per-trillion range. Detecting and quantifying PFAS is crucial for understanding contamination and managing health risks. Scientists use targeted analysis to identify and quantify specific PFAS compounds accurately.
You can also read: PFAS at a Glance: Challenges and Industry Impacts
Targeted analysis plays a critical role in the detection and quantification of PFAS. Despite its advantages, this method is not without challenges. Many PFAS compounds remain unidentified, and characterization protocols are available for only a small subset. This approach relies on validated reference materials, which enhance accuracy and limit its scope depending on the availability of standards.
PFAS exist in everyday products. Courtesy of Sartorius.
The targeted PFAS analysis process begins with instrument calibration. Calibration is essential to ensure that instruments like LC-MS/MS and GC-MS perform accurately throughout the analysis. Scientists calibrate their instruments using certified reference materials containing known PFAS concentrations, which helps guarantee consistent and comparable results.
Next, sample preparation takes place. PFAS compounds often occur in complex matrices such as water, soil, air, and food, and their extraction requires specific techniques. Methods like Solid-Phase Extraction (SPE) and Liquid-Liquid Extraction (LLE) concentrate PFAS from the sample, improving detection limits and sensitivity. These steps are labor-intensive but necessary to detect and quantify the compounds of interest.
Following this, chromatographic separation is a crucial step in the process. Liquid chromatography (LC) works for non-volatile PFAS, while gas chromatography (GC) is ideal for volatile compounds. This step separates individual PFAS, enabling mass spectrometry to analyze them.
Once separated, mass spectrometry provides both qualitative and quantitative data. This step determines the concentration of each compound in the sample.
Modern laboratories employ specialized instruments for targeted PFAS analysis. Liquid Chromatography-Mass Spectrometry (LC-MS/MS) is known for its sensitivity and precision. It effectively identifies and quantifies known PFAS compounds, ensuring high reproducibility across studies.
Gas Chromatography-Mass Spectrometry (GC-MS) is suitable for volatile PFAS compounds. It excels at detecting compounds with low volatility and a wide molecular weight range. Ion Chromatography (IC) enhances the separation of ionic PFAS before mass spectrometric detection.
Pyrolysis-Gas Chromatography-Mass Spectrometry (PY-GC-MS) is particularly useful for analyzing polymeric PFAS compounds. It thermally decomposes samples into smaller, volatile components for subsequent analysis.
Tandem Mass Spectrometry (MS/MS) provides highly sensitive detection by fragmenting PFAS molecules and identifying them based on their mass-to-charge ratio. High-Resolution Mass Spectrometry (HRMS) techniques, like Quadrupole Time-of-Flight (QTOF-MS), allow for better identification of unknown PFAS by detecting their molecular structures and fragmentation patterns.
The National Institute of Standards and Technology (NIST) plays a key role in the development of Standard Reference Materials (SRMs) to support PFAS analysis. These reference materials include solutions for drinking water, aqueous samples, and food matrices. They are essential for ensuring accurate and comparable PFAS analysis across laboratories. NIST’s SRMs help laboratories validate their methods and establish reliable benchmarks for PFAS detection.
Mass spectrum for PFOS, a widespread PFAS. Courtesy of NIST.
While targeted analysis is highly accurate, it faces significant challenges. One of the main limitations is the limited availability of reference standards. Many PFAS compounds still lack certified reference materials, which hinders the ability to expand the analysis beyond the well-characterized substances. This limitation means that analysis only works for a select group of PFAS, leaving many others undetected.
The process itself is also time-consuming. Sample preparation and analysis can take several hours or even days, depending on the complexity of the sample and the specific techniques used. This extended timeline leads to increased operational costs and a reduced capacity for high-throughput analysis, which may limit the widespread adoption of these methods in large-scale monitoring programs.
Despite its sensitivity, targeted analysis can struggle to detect PFAS at extremely low concentrations. Some PFAS compounds exist at levels too low for traditional methods to detect effectively, requiring advanced techniques or the development of more sensitive instruments. These limitations highlight the need for continuous improvements in both methodology and technology.
Contamination remains one of the most significant risks in PFAS analysis. Many laboratory materials, including tubing, vials, and filters, contain fluoropolymers that can introduce unwanted PFAS into samples. To mitigate this risk, laboratories implement rigorous contamination control measures. One of the most important precautions is the use of PFAS-free equipment and consumables, all of which undergo frequent testing to ensure their integrity.
Additionally, delay columns in LC-MS/MS systems help separate background PFAS from sample PFAS, reducing the likelihood of false positives. Quality control procedures, such as method blanks and spiked samples, help validate the analysis and confirm that there is no contamination present.
To ensure consistent and reliable results, regulatory agencies have established standardized methods for PFAS analysis. One widely adopted method is EPA 1633, which provides a validated approach for detecting PFAS in environmental samples. These include water, soil, and biosolids, using LC-MS/MS. Other relevant methods include ASTM D8421 and ASTM D8535, which provide additional guidance for PFAS testing across different matrices.
EPA Methods 537.1 and 533 ensure accurate PFAS detection in drinking water using SPE and LC-MS/MS. Method 537.1 targets longer-chain PFAS, while Method 533 detects short-chain compounds, covering 29 PFAS when combined. These methods provide standardized protocols for sampling, preparation, and analysis.
Targeted PFAS analysis is a precise method for detecting and quantifying PFAS contamination. However, the method is not without its limitations, including the restricted availability of reference materials, the time-consuming nature of the process, and contamination risks. Despite these challenges, advancements in the development of new reference materials, such as those from NIST, and improvements in analytical techniques will continue to drive progress in PFAS detection. As methods evolve, the emphasis will remain on ensuring accuracy using state-of-the-art instrumentation.
New findings reveal microplastics in brain tissue, raising concerns about links to cognitive decline. Microplastic…
The world is bracing to adapt as the new administration reveals its hand. Changes in…
ANTEC® 2025 brings together scientists, engineers, and industry leaders to shape the future of plastics…
The past year marked significant growth for Bcomp, a leader in flax-based bio-composites, with achievements…
The global composites market is experiencing steady and significant growth. Market analysts expect that it…
The extrusion coating market is evolving to provide sustainable alternatives that meet current packaging technical…
View Comments
this is a really good piece of analytical equipment I like your test parameters and new standards for calibrating!
the question that arises in today's plastics market is how do we use the recycle material in new products to lower the carbon footprint and yet still tests for the forever chemicals that we know will be in the recycle plastic? wood testing methods as precise as these are it will detect the forever chemicals and make the product band from commercial production which results in using no recycle material that contains these chemicals.