Screening of per- and polyfluoroalkyl substances (PFAS) in cosmetics: Utilizing a new combustion-ion chromatography system for total organic fluorine (TOF) analysis

Significance of the topic

Per- and polyfluoroalkyl substances (PFAS) are frequently used in cosmetics to impart desirable properties such as water resistance, spreadability and long wear. Their strong C–F bonds and persistence raise human-health and environmental concerns, prompting regulatory action (for example California AB 2771). Conventional targeted LC–MS assays detect specific PFAS but miss unknown, polymeric or precursor fluorinated species. Total organic fluorine (TOF) screening by combustion-ion chromatography (C-IC) provides a complementary, broad indicator of organically bound fluorine and helps prioritize samples for targeted identification methods.

Objectives and study overview

This application note describes a streamlined workflow using the Thermo Scientific Cindion C-IC system combined with a Dionex Inuvion IC to:

• Quantify total fluorine (TF) in cosmetic solids and liquids by combustion followed by IC detection of fluoride.
• Measure total inorganic fluorine (TIF) by aqueous extraction and direct IC injection.
• Calculate TOF as TF minus TIF to screen for organically bound fluorine that is potentially attributable to PFAS.
• Evaluate method performance (calibration, detection limits, recovery, precision) and apply the workflow to ten commercial cosmetics (lipsticks, mascaras, foundations).

Used instrumentation

The analytical platform and key consumables used in this work:

• Cindion combustion/absorption module (C-IC) with Z-fold combustion tube design.
• Dionex Inuvion IC system with Reagent-Free Ion Chromatography (RFIC) and Dionex AS-AP autosampler.
• Dionex IonPac AS24 analytical column (2 × 250 mm) and AG24 guard (2 × 50 mm).
• Dionex EGC 500 KOH eluent cartridge and CR-ATC 600 anion trap column.
• Dionex ADRS 600 anion dynamically regenerated suppressor (2 mm) in recycle mode (or NGES-A equivalent).
• Chromeleon Chromatography Data System (CDS) for unified control and data processing.
• Laboratory consumables: pre-baked ceramic combustion cups, PES 0.2 µm filters, HDPE bottles, microcentrifuge tubes.

Methodology

Sample preparation and measurement strategy:

• TF (combustion mode): 5–50 mg of cosmetic was placed in pre-baked ceramic boats and combusted in the Cindion module (∼1100 °C; O2 and Ar flows). Combustion products were absorbed in 7 mL DI water; 25 µL of absorbate was injected to IC. TF is determined as fluoride formed from all fluorine species in the sample.
• TIF (direct injection mode): 25–100 mg of sample was water-extracted (1.5 mL DI water, sonication 30 min, centrifugation 15,000 × g, filtration 0.2 µm) and the aqueous extract was analyzed by IC to quantify inorganic fluoride.
• TOF calculation: TOF = TF − TIF.
• Chromatography: hydroxide eluent gradient (KOH) was chosen to separate fluoride from the water dip and other anions; suppressed conductivity detection with a 25 µL loop, flow 0.3 mL/min, column at 30 °C, run time 20 min.
• Calibration: seven-point fluoride calibration (1–100 mg/L) prepared from 1000 mg/L standard; combusted standards were used for combustion-mode calibration to align with EPA Method 1621. Quadratic fit with regression coefficients >0.999; calibration recoveries within 95–110% (EPA acceptance 80–120%).
• Quality control: boat blanks, extraction blanks, spiked samples (PFOS) for recovery, and repeated injections to monitor carryover and precision.

Main results and discussion

Analytical performance:

• Combustion efficiency: combustion of a PFOS standard (0.35 mg/mL methanolic solution) produced a 98.5% recovery of fluorine, confirming effective conversion to fluoride.
• Calibration linearity and reproducibility met EPA Method 1621 criteria (RSE <10%, regression coefficient >0.999).
• Method detection limits (MDL): TF MDLb calculated as ~0.9 µg/g (0.9 ppm) assuming a 50 mg sample; TIF MDLs reported as 37.8 ng/g assuming a 25 mg sample (calculated from replicate analysis of a low-level standard).
• Accuracy and precision: TF spike recoveries (PFOS) in matrix ranged 98–110%; TIF recoveries (fluoride spikes) ranged 95–115%. Triplicate RSDs were typically <5% for repeat analyses; RSD <10% for TF >100 ppm and <20% for TF <100 ppm.

Application to cosmetics (ten consumer products):

• Five of ten products (three lipsticks, two mascaras) showed TOF >100 ppm (µg/g), with the highest TOF values in mascara samples (~1965 and 2089 µg/g), indicating substantial organically bound fluorine consistent with added fluorinated ingredients or PFAS-containing formulations.
• In most samples TIF contribution was negligible (<1 ppm), but three products showed elevated TIF (>8 ppm), demonstrating the need to subtract inorganic contributions when estimating organic fluorine.
• Chromatographic separation allowed reliable resolution of fluoride from matrix anions and the water dip, supporting robust quantification.

Interpretation: Elevated TOF values serve as a conservative screening flag for the presence of intentionally added fluorinated organics, including PFAS. Because TOF is non-specific, follow-up targeted analyses (e.g., LC–MS/MS) are necessary to identify and quantify individual PFAS species and to confirm regulatory compliance with laws such as California AB 2771.

Benefits and practical applications

Practical advantages of the C-IC TOF workflow:

• Broad inclusivity: measures fluorine from all organic fluorinated species, including unknown, polymeric or precursor PFAS that lack analytical standards for LC–MS detection.
• High throughput screening: streamlined combustion plus IC analysis enables relatively rapid triage of many samples to prioritize targeted confirmations.
• Regulatory support: provides laboratories and manufacturers with an objective screening metric to support compliance monitoring and supply-chain surveillance under emerging PFAS restrictions.
• Robust quantitation: validated calibration, high combustion efficiency and acceptable recoveries and precision make the approach suitable for routine screening.

Limitations and operational considerations

Key limitations to be considered:

• Non-specificity: TOF does not identify which PFAS or fluorinated moieties are present; complementary targeted methods are required for speciation and regulatory reporting.
• Potential interferences and background: rigorous blanking (boat blanks, extraction blanks) is essential; carryover prevention is important for high-fluorine samples.
• Detection limit dependence: MDL is influenced by sample mass and background; low-level organofluorine near the MDL may be difficult to interpret without additional corroborative data.

Future trends and opportunities

Areas likely to shape future use and development of TOF screening by C-IC:

• Method standardization and regulatory acceptance: broader adoption of guidance such as EPA Method 1621 and harmonized reporting criteria will strengthen TOF utility in compliance workflows.
• Lowering detection limits: instrumentation and procedural refinements to reduce background and increase sensitivity will expand applicability to lower-concentration products.
• Integrated workflows: coupling TOF screening with automated sample handling and targeted LC–MS pipelines will enable rapid confirmatory analysis after initial flags.
• Characterization of polymeric/unknown fluorinated materials: analytical strategies to combine TOF with non-target and suspect-screening mass spectrometry will improve identification of novel PFAS and fluorinated polymers in complex formulations.
• Expanded matrices and surveillance programs: deployment in manufacturing QC, regulatory surveillance, and market screening programs to track compliance with PFAS bans or restrictions.

Conclusion

The Thermo Scientific Cindion C-IC combined with a Dionex Inuvion IC provides a validated, practical TOF screening workflow for cosmetics. The method delivers reliable combustion conversion, robust IC separation of fluoride, and acceptable precision and accuracy. TOF is a useful screening metric to identify products likely to contain intentionally added fluorinated organics or PFAS, supporting targeted follow-up analyses and regulatory compliance efforts. Careful blank control, appropriate calibration and follow-up speciation remain necessary to interpret TOF results in a regulatory context.

Reference

1. Reuters. Beauty products meet the “forever chemicals” challenge. Reuters, September 22, 2025.
2. California State Legislature. California Assembly Bill 2771 (PFAS-Free Cosmetic Act).
3. Scheringer, M.; Trier, X.; Cousins, I. T.; et al. Fluorinated compounds in cosmetic products. Environmental Science & Technology 2017, 51 (13), 7489–7497.
4. Hu, J.; Rumachik, N. Technical Note TN003853: Configuring the Thermo Scientific Cindion C-IC System for a 2-in-1 Operation—Seamless Switching between Combustion-IC and Standalone IC with an AS-AP Autosampler; Thermo Fisher Scientific: Sunnyvale, CA, 2025.
5. US Environmental Protection Agency. Method 1621: Determination of Adsorbable Organic Fluorine (AOF) in Aqueous Matrices by Combustion Ion Chromatography (CIC) (EPA 821-R-24-002); U.S. EPA: Washington, DC, 2024.
6. US Environmental Protection Agency. Definition and Procedure for the Determination of the Method Detection Limit, Revision 2; U.S. EPA: Washington, DC, 2016.