Rapid Screening and confrmation analysis of polycyclic aromatic hydrocarbons (PAHs) with DART mass spectrometry

Significance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) are regulated contaminants due to their potential health risks when present in consumer goods that contact the mouth or food. Rapid screening methods are essential to meet regulatory demands and improve laboratory throughput.

Objectives and Overview of the Study

This study aims to develop a rapid screening protocol using direct analysis in real time mass spectrometry (DART-MS) for PAHs and to integrate liquid chromatography (LC) with DART-MS for confirmation and isomer differentiation.

Methodology

Standards of typical PAHs were analyzed directly by DART-MS in both positive and negative ion modes. To achieve chromatographic separation of structural isomers, a reverse-phase HPLC step was introduced with flow splitting to match DART ionization requirements.

Instrumental Setup

• DART-OS ion source with helium gas at 300–500 °C
• Shimadzu LCMS-2020 single/triple quadrupole mass spectrometer
• High-speed polarity switching (15 ms) and scanning rate of 15 000 u/s
• Unison UK-C8 column (2.0 mm × 100 mm, 3 µm) with 1 mM ammonium formate/acetonitrile (75/25)
• Flow rate split: 0.2 mL/min to LC, 10 µL/min to DART

Main Results and Discussion

DART-MS detected protonated [M+H]+ and oxygenated [M+O–H]– ions for benzo[a]anthracene (m/z 229/243), acenaphthene, anthracene, and others. Structural isomers pyrene and fluoranthene produced identical negative ions at m/z 217 and required LC separation. LC-DART-MS enabled clear retention time differentiation and selective ion monitoring in SIM mode for confirmation.

Benefits and Practical Applications

The combined DART-MS and LC-DART-MS approach offers minimal sample preparation, fast throughput for screening, and robust confirmation of PAH identities, making it suitable for quality control, food safety, and environmental monitoring.

Future Trends and Possibilities

Emerging developments may include quantitative DART-MS methods, expanded PAH libraries, portable and automated sampling platforms, and integration with advanced data analysis tools for field deployments.

Conclusion

Coupling DART-MS with HPLC provides an efficient workflow for rapid screening and reliable confirmation of PAHs, meeting regulatory requirements and enhancing laboratory productivity.

References

Shimadzu Application Note PO-CON1455E, First Edition June 2014