Targeted LC-MS methods play a central role in PFAS analysis, but they do not capture the full contamination picture. In a conversation with David Oliva of Concentrating on Chromatography, Jay Gandhi, PhD, Vertical Market Manager at Metrohm USA, discussed how ion chromatography, absorbable organic fluorine (AOF), combustion ion chromatography (CIC), and IC-MS can help laboratories take a broader view of PFAS contamination.
How Ion Chromatography Moved Beyond Water Analysis
Gandhi’s work in ion chromatography began during his time on a NASA Mars exploration project, where IC supported water recovery research in zero gravity. The technology helped assess anion and cation balance, micronutrients for agricultural use, and water purity for astronauts.
That early exposure led Gandhi into IC instrumentation and applications. Over the course of his career, he has seen the technique move well beyond its early use in water analysis.
Ion chromatography has supported water quality testing since the 1970s. Today, it serves laboratories working in food and beverage, environmental analysis, semiconductor manufacturing, battery recycling, and other fields. PFAS analysis now represents one of its most urgent applications.
Why PFAS Changed the Analytical Challenge
PFAS compounds have been used for decades in consumer, industrial, and firefighting applications. Gandhi points to nonstick cookware, aqueous film-forming foam (AFFF), textiles, food packaging, water-resistant fabrics, and other treated materials as sources that can contribute to environmental contamination.
His interest in PFAS analysis grew from early work on PFOA and PFOS, followed by a 2015 research paper from Sweden that used combustion ion chromatography for total fluorine analysis. Later collaborations with researchers at Clarkson University and Harvard University, especially around AFFF, helped bring PFAS analysis into sharper focus.
The challenge lies in scale. Laboratories may target dozens or even hundreds of PFAS compounds by LC-MS, but that list still represents a small fraction of the compounds and transformation products that may exist in the environment.
Why Targeted LC-MS Captures Only Part of the Picture
Targeted LC-MS gives laboratories compound-specific information. It offers sensitivity and selectivity for known PFAS compounds, making it essential for confirmatory analysis and regulatory testing.
But targeted workflows depend on defined analyte lists, suitable separation, matrix control, and available isotope-labeled internal standards. Gandhi notes that isotope-labeled standards can cost a great deal and may not exist for every compound of interest.
This creates a practical problem: laboratories can spend significant resources measuring a small portion of the total PFAS burden. Gandhi frames targeted LC-MS as a strong starting point, but not the full answer.
What AOF Adds to PFAS Analysis
AOF gives laboratories a broader screening approach. Instead of identifying individual PFAS compounds, AOF methods assess a larger pool of organic fluorine.
This can help laboratories estimate fluorinated contamination that targeted LC-MS may miss. Gandhi describes AOF as a complementary technique rather than a replacement for LC-MS.
That distinction matters. LC-MS answers the question, “Which specific PFAS compounds are present?” AOF helps answer a different question: “How much broader fluorinated material might be present?”
How Combustion Ion Chromatography Supports Total Fluorine Screening
Combustion ion chromatography applies high-temperature combustion to break carbon-fluorine bonds. The process converts fluorinated compounds into fluoride ions, which ion chromatography then measures.
Gandhi described CIC as an evolution of older total organic halogen analyzer approaches. By using ion chromatography as the detector, the workflow gains sensitivity and selectivity for individual halides, including fluoride.
For PFAS analysis, the strength of CIC lies in its broader view. It does not depend on a predefined list of PFAS compounds. Instead, it can provide an estimate of total fluorine-related contamination.
Sample Preparation Remains a Critical Barrier
Sample preparation can shape the quality of AOF and total fluorine results. One major challenge comes from inorganic fluoride.
Gandhi used drinking water and wastewater as examples. Fluoride added to drinking water can later enter wastewater, creating a high inorganic fluoride background. Laboratories may then need to detect low levels of organic fluorine against a much larger fluoride signal.
Background contamination can come from other sources as well. Gandhi highlighted environmental fluoride, air handling systems, refrigerants, and carbon materials used in sample preparation as possible contributors.
These factors make material selection, fluoride background control, and interference checks essential for reliable AOF and CIC workflows.
How EPA Method 1621 Reached Standardization
Gandhi discussed the development of EPA Method 1621 and related standards work as a collaborative process. He emphasized that many scientists contributed across industry, government, and standards organizations.
The method development path included work in Europe, DIN in Germany, ISO activity, ASTM D19, and collaboration with the US EPA. Gandhi describes a process shaped by discussion, debate, experimentation, and data.
For laboratories, that standardization work matters because it gives AOF and combustion IC a clearer role in PFAS screening and environmental testing.
Where PFAS Regulations May Move Next
Regulatory attention continues to move beyond drinking water. Gandhi points to wastewater, landfills, textiles, food packaging, and consumer products as important areas of focus.
He expects AOF to begin as a screening tool for gross contamination, particularly in wastewater and permitting contexts. Over time, he sees the potential for broader regulatory use.
The direction reflects a wider shift in PFAS control. Regulators and laboratories need tools that can assess contamination sources, treatment efficiency, and the broader fluorinated burden across complex matrices.
The Role of IC-MS in Polar PFAS Analysis
The conversation also covered IC-MS and IC-MS/MS. Gandhi highlights their value for small, highly polar PFAS compounds, including trifluoroacetic acid (TFA) and difluoroacetic acid (DFA).
These compounds can challenge AOF workflows because they may not adsorb well onto carbon materials. Direct injection IC methods, coupled with mass spectrometric detection, can help separate these compounds from common anions in water while improving detection confidence.
Gandhi also notes that IC-MS approaches can support analysis of other polar compounds, including pesticides such as glyphosate and glufosinate.
A Complementary Toolkit for PFAS Testing
Gandhi's central message is that no single method tells the full PFAS story. Targeted LC-MS remains essential for compound-specific analysis, but AOF and combustion IC can reveal contamination that targeted lists may miss.
IC-MS and IC-MS/MS add further value for small polar compounds that may escape other workflows. High-resolution mass spectrometry can support deeper investigation of transformation products and unknowns.
Together, these approaches give laboratories a broader framework for PFAS analysis. As sample preparation improves and background fluoride decreases, Gandhi expects combustion IC workflows to reach lower detection limits and play a larger role in screening.
For analytical scientists, the takeaway is practical: PFAS analysis now requires a layered strategy. Targeted methods identify known compounds. AOF and CIC help assess the wider fluorinated burden. IC-MS expands the view into polar, water-soluble compounds that demand specialized separation and detection.
