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Based on an episode of the Concentrating on Chromatography podcast hosted by David Oliva, General Manager of Organomation
Per- and polyfluoroalkyl substances (PFAS) have rapidly become one of the most important analytical challenges facing environmental laboratories today. As regulators continue expanding scrutiny of PFAS contamination in water, soil, textiles, food packaging, and industrial waste streams, analytical scientists are under increasing pressure to develop methods capable of detecting not only targeted PFAS compounds, but also the vast universe of unknown fluorinated substances present in the environment.
In a recent episode of the Concentrating on Chromatography podcast, David Oliva spoke with Jay Gandhi, PhD, Vertical Markets Manager at Metrohm USA, about the evolution of PFAS analysis, the growing role of adsorption-based total fluorine methods such as AOF (Adsorbable Organic Fluorine), and the development of EPA 1621 and ISO 18127 standards.
The discussion highlighted a major shift occurring within environmental testing laboratories: the movement from narrowly targeted PFAS analysis toward more comprehensive approaches capable of assessing total fluorinated contamination.
For laboratories involved in sample preparation, evaporation, chromatography, and mass spectrometry workflows, the interview also underscored the increasing importance of robust sample concentration and cleanup techniques in supporting ultra-trace PFAS analysis.
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The Rise of PFAS as a Global Analytical Challenge
According to Gandhi, PFAS contamination has evolved from a niche environmental concern into a mainstream analytical priority over the past decade.
PFAS compounds have been used extensively for more than sixty years in products ranging from nonstick cookware and firefighting foams to waterproof textiles and industrial manufacturing materials. Their strong carbon-fluorine bonds make them highly resistant to degradation, leading to the nickname “forever chemicals.”
One of the most difficult aspects of PFAS analysis is the sheer number of compounds involved.
“Targeted” PFAS analysis typically focuses on a defined list of compounds such as PFOA and PFOS using LC-MS/MS methods. However, Gandhi noted during the interview that these targeted lists often represent only a small fraction of the fluorinated compounds potentially present in environmental samples.
This analytical gap has driven growing interest in sum-parameter methods such as AOF.
What Is AOF?
AOF, or Adsorbable Organic Fluorine, is designed to measure the total amount of adsorbable organofluorine compounds present within a sample rather than focusing exclusively on individual PFAS species.
The approach provides a broader picture of fluorinated contamination.
In many cases, laboratories performing targeted LC-MS/MS analysis may identify only a small percentage of the total fluorine actually present in a sample. AOF methods help estimate the unknown fraction.
This distinction is becoming increasingly important as regulatory agencies and researchers recognize that many fluorinated compounds remain unidentified or are not routinely included in targeted methods.
The ability to compare targeted PFAS concentrations against total fluorine measurements can help laboratories and regulators better understand the extent of contamination.
Combustion Ion Chromatography and Total Fluorine Analysis
One of the central themes of the interview was the growing role of combustion ion chromatography (CIC) in PFAS workflows.
CIC combines combustion with ion chromatography detection. In a typical workflow, fluorinated compounds are combusted at high temperatures, converting organically bound fluorine into hydrogen fluoride. The resulting fluoride ions are then captured and quantified using ion chromatography.
This approach enables laboratories to measure total fluorine content without requiring identification of every individual PFAS compound.
According to Gandhi, combustion ion chromatography gained significant momentum around 2015, particularly following early European research efforts involving AOF analysis.
Researchers began recognizing the value of holistic fluorine screening approaches, especially for environmental samples containing complex mixtures of known and unknown PFAS compounds.
Today, CIC-based workflows are increasingly used for:
- Water analysis
- Wastewater testing
- Firefighting foam investigations
- Textile screening
- Food packaging analysis
- Industrial contamination studies
- Semiconductor and electronics applications
The analytical flexibility of ion chromatography has also expanded dramatically over the past several decades.
During the interview, Gandhi described how IC initially gained widespread adoption for routine anion and cation analysis in water testing following its introduction in the 1970s. Over time, however, the technique evolved into a highly versatile platform supporting environmental, food, beverage, pharmaceutical, semiconductor, and energy applications.
Why Sample Preparation Matters More Than Ever
For laboratories performing PFAS analysis, sample preparation remains one of the most critical aspects of the workflow.
Ultra-trace PFAS measurements often require extensive extraction, concentration, and cleanup procedures before chromatographic analysis can occur.
Environmental samples frequently contain:
- Complex matrices
- Organic interferences
- Variable fluorinated compound distributions
- Trace-level analytes in parts-per-trillion concentrations
As detection limits become increasingly stringent, laboratories must carefully optimize evaporation and concentration procedures while minimizing contamination risk.
This is particularly important for:
- Solid-phase extraction (SPE) eluates
- Solvent exchange procedures
- Concentration of aqueous extracts
- Preparation of samples for LC-MS/MS analysis
- Concentration of combustion extracts
Nitrogen blowdown evaporation systems remain widely used throughout PFAS workflows because they provide gentle concentration under controlled temperatures while reducing the risk of analyte loss.
Many environmental laboratories rely on nitrogen evaporation systems to improve detection sensitivity before instrumental analysis.
Because PFAS compounds may adsorb to certain surfaces or appear as background contaminants in laboratory materials, analysts must also carefully evaluate consumables, tubing, solvents, and sample handling procedures.
The growing complexity of PFAS analysis has therefore elevated the importance of contamination control throughout the entire analytical workflow.
EPA 1621 and ISO 18127: Standardizing AOF Analysis
One of the most fascinating sections of the interview focused on the development of EPA 1621 and ISO 18127.
Gandhi emphasized that the creation of these methods was highly collaborative and involved scientists from government agencies, instrument manufacturers, standards organizations, and analytical laboratories.
The work began with early European research and eventually progressed through Germany’s DIN standards organization before advancing into ISO standardization efforts.
In parallel, ASTM committees and the U.S. EPA worked to adapt and validate the methodology for broader adoption.
According to Gandhi, the development process spanned roughly five years and required extensive interlaboratory collaboration.
One of the biggest challenges involved achieving consensus across multiple stakeholders.
Analytical standardization is rarely straightforward. Laboratories, regulators, vendors, and researchers may all have differing priorities regarding:
- Sensitivity
- Robustness
- Sample throughput
- Instrument compatibility
- Reproducibility
- Cost
- Regulatory applicability
Despite these challenges, Gandhi described the process as a successful example of scientific collaboration.
He noted that while technical debates were common, the final decisions ultimately depended on experimental data.
This collaborative framework is particularly important in PFAS analysis because the field continues evolving rapidly.
The Emerging Importance of TFA Analysis
The interview also touched on increasing concern surrounding trifluoroacetic acid (TFA).
TFA is a highly persistent fluorinated compound that can form through degradation of certain PFAS compounds and fluorinated refrigerants.
Because TFA is highly polar and difficult to analyze using some traditional PFAS workflows, laboratories are exploring alternative analytical techniques including ion chromatography-mass spectrometry (IC-MS) and IC-MS/MS.
These hyphenated techniques combine the separation capabilities of ion chromatography with the selectivity and sensitivity of mass spectrometry.
As concern surrounding short-chain and ultrashort-chain PFAS compounds continues growing, IC-MS methods may play an increasingly important role in environmental analysis.
Final Thoughts
The conversation between David Oliva and Jay Gandhi highlighted just how quickly PFAS analysis is evolving.
What began as targeted monitoring of a relatively small number of compounds has expanded into a much broader effort to understand total fluorinated contamination across environmental and industrial systems.
The development of EPA 1621 and ISO 18127 represents an important milestone in that evolution.
Equally important, however, is the collaborative scientific process behind these standards.
As Gandhi emphasized during the interview, meaningful progress in PFAS analysis requires cooperation among researchers, instrument vendors, laboratories, regulators, and standards organizations.
For laboratories involved in chromatography, mass spectrometry, and environmental analysis, the coming years will likely bring continued innovation in both instrumentation and sample preparation workflows.
And as the PFAS landscape grows more complex, holistic analytical approaches such as AOF may become increasingly central to understanding the true extent of fluorinated contamination.