A Sample Prep-Free Analysis of Perfluorinated Carboxylic Acids with “Smart IS+” and “SMCI+” - Environmental Monitoring -

Importance of the Topic

Perfluorinated carboxylic acids are highly persistent environmental pollutants with significant bioaccumulation and health implications. Reliable analytical methods are essential for monitoring these “forever chemicals” in environmental and biological matrices.

Study Objectives and Overview

This study presents a direct sample inlet approach combined with Shimadzu’s Smart IS+ and SMCI+ setups for qualitative analysis of six PFCAs by GC/MS, aiming to eliminate derivatization and streamline environmental monitoring workflows.

Methodology and Instrumentation

Standard solutions of six PFCAs (PFHpA, PFOA, PFNA, PFDA, PFTriA, PFTA) were prepared at 5000 ppm in methanol. Samples (1 µL) were introduced into a direct inlet probe, heated with a ramp to 450°C, and analyzed using both electron ionization (EI) and positive chemical ionization (PCI) modes (quick CI with isobutane and SMCI with methanol). Mass spectra were acquired on a Shimadzu GCMS-TQ8050 NX in the m/z 50–800 range.

Used Instrumentation

• Shimadzu GCMS-TQ8050 NX triple quadrupole GC-MS
• Direct Inlet (DI) probe
• Smart IS ion source (EI and CI capable)
• SMCI unit (methanol-mediated CI)

Main Results and Discussion

EI mode yielded library-matched spectra for PFHpA–PFDA with similarity indices >80 for longer chains. QCI and SMCI modes produced dominant [M+H]+ ions and characteristic CF2 loss series at 50 u intervals, with a base peak at m/z 131 ([C3F5]+). SMCI exhibited higher protonation efficiency, while QCI offered distinct confirmatory fragmentation.

Benefits and Practical Applications

• Eliminates time-consuming derivatization steps.
• Rapid screening of PFCAs with a single probe-based workflow.
• Easy switching between EI and CI modes via Smart IS+.
• Safe reagent use in SMCI+ using methanol instead of flammable gases.

Future Trends and Potential Applications

Expanding negative CI capabilities to enhance sensitivity for fluorinated analytes; applying probe-based analysis to a broader range of PFAS compounds; integrating high-resolution and ambient ionization techniques for real-time environmental and food safety monitoring.

Conclusion

The Smart IS+ and SMCI+ configurations enable direct, preparation-free GC/MS analysis of perfluorinated carboxylic acids, offering a streamlined, safe, and reliable approach for environmental monitoring of persistent PFAS pollutants.

Reference

Chua Chun Kiang, Jackie, Riki Kitano. “A Sample Prep-Free Analysis of Perfluorinated Carboxylic Acids with Smart IS+ and SMCI+.” Shimadzu Corporation, March 2021.