GC-CI-MS/MS Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) Isomers in Salami

Importance of the Topic

Polycyclic aromatic hydrocarbons (PAHs) such as benzo[a]pyrene are environmental contaminants with carcinogenic potential. Their presence in food and water demands sensitive and selective analytical methods. Accurate separation of PAH isomers prevents false positives and ensures reliable monitoring in quality control, regulatory compliance and risk management.

Objectives and Study Overview

The study aimed to develop and validate a gas chromatograph triple quadrupole tandem mass spectrometry method using chemical ionization (CI-MS/MS) for the separation and quantification of PAH isomers in salami. Key targets included challenging pairs such as chrysene versus triphenylene, some PAHs listed in regulatory guidelines.

Instrumentation

• GCMS-TQ8050 NX triple quadrupole gas chromatograph mass spectrometer
• Column: SH-I-PAH, 60 m × 0.25 mm I.D., df 0.10 μm
• Injection: splitless, 1 μL; inlet temperature 250 °C
• Carrier gas: helium at linear velocity 42.5 cm/s
• Oven program: 50 °C hold 2 min; 40 °C/min to 200 °C; 25 °C/min to 250 °C hold 3 min; 15 °C/min to 350 °C hold 5 min
• Ion source: positive chemical ionization (PCI) with methane; interface 330 °C; source 250 °C
• Acquisition: multiple reaction monitoring (MRM)

Methods and Analytical Workflow

The method combined QuEChERS sample preparation and GC-CI-MS/MS analysis. A crushed salami sample (10 g) was hydrated with water, fortified with PAH standards (25 ng/mL) and deuterated internal standard chrysene-d12 (10 ng/mL), then extracted with acetonitrile using non-buffered QuEChERS salts. After centrifugation, 3 mL of extract underwent dispersive solid-phase clean-up with Z-sep sorbent. The cleaned supernatant was analyzed by GC-CI-MS/MS, monitoring specific transitions for high selectivity and a high-intensity [M+H]+ transition for sensitivity.

Main Results and Discussion

The CI process formed stable adducts such as [M+C2H5]+, enabling differentiation of isomeric PAHs. In mixed standard tests at 50 ng/mL, chrysene and benzo[a]anthracene were resolved selectively by characteristic transitions, while triphenylene displayed distinct fragmentation due to higher resonance stability. Calibration curves for chrysene displayed excellent linearity (R2>0.999) over 1–500 ng/mL, with limits of quantification near 0.1 ng/mL. Signal-to-noise ratios exceeded 11 for low-abundance transitions and 59 for [M+H]+ at 1 ng/mL. Analysis of spiked salami confirmed the method’s capacity to separate chrysene and triphenylene, with 105.9% recovery for chrysene when using specific transitions, compared to 73.7% for non-selective transitions.

Benefits and Practical Applications of the Method

• High selectivity: CI adducts and targeted MRM transitions isolate isomeric PAHs, reducing false positives.
• High sensitivity: Protonated ion [M+H]+ delivers low detection limits (~0.1 ng/mL) and robust quantification.
• Efficient sample preparation: Simple QuEChERS workflow enables rapid processing of complex food matrices.
• Regulatory compliance: Accurate quantification of regulated PAHs supports food safety and environmental monitoring.

Future Trends and Applications

CI-MS/MS methods are expected to expand to other challenging isomeric contaminants and diverse matrices. Integration with automated sample handling and high-throughput instrumentation will enhance laboratory efficiency. Advanced data processing, including AI-driven algorithms, may further streamline MRM interpretation and facilitate real-time quality control in industrial environments.

Conclusion

Chemical ionization tandem MS using the Shimadzu GCMS-TQ8050 NX provides a powerful approach for separating and quantifying PAH isomers in food samples. By leveraging reagent-gas adduct chemistry and targeted MRM transitions, this method achieves superior selectivity, sensitivity and robustness, fulfilling the demands of modern analytical and regulatory laboratories.

References

No formal literature list was provided in the source text.