Analysis of Polycyclic Aromatic Hydrocarbons (PAH) and Hydroxylated PAH Metabolites in Plasma and Urine Using High Resolution GC/Q TOF

Significance of the Topic

Polycyclic aromatic hydrocarbons are ubiquitous environmental pollutants generated by incomplete combustion of organic materials and recognized as carcinogens. Hydroxylated PAH metabolites serve as sensitive biomarkers of recent exposure in biological samples. Monitoring these compounds at trace levels in plasma and urine is critical for environmental health assessment and occupational safety.

Objectives and Study Overview

This study evaluated a high-resolution GC Q TOF workflow combining targeted quantification and untargeted screening for PAHs and their hydroxylated metabolites in pooled human plasma and urine. The aim was to develop a single analytical approach capable of sensitive detection of known targets while discovering additional biologically relevant xenobiotics.

Methodology and Instrumentation

Sample Preparation

• L L extraction of plasma and urine with hexane acetone mixture and phase separation aided by magnesium sulfate and sodium chloride
• Spike with deuterated internal standards and PAH metabolites at 0.2 ppb to 2 ppm
• Derivatization using MSTFA and pyridine

Instrumentation

• Agilent 7890B GC system coupled to 7250 GC Q TOF high resolution accurate mass spectrometer
• DB 5MS UI column 30 m by 0.25 mm by 0.25 µm
• Electron ionization at standard and low energies including 70 eV, 15 eV, and 12 eV
• Oven temperature program from 70°C initial hold to final 325°C
• Helium carrier gas at 1.2 mL per minute and mass range 50 to 650 m/z
• Data processing with MassHunter Qualitative and Quantitative Analysis software, use of PCDL for targeted compounds and Unknowns Analysis with NIST17.L library

Main Results and Discussion

An accurate mass Personal Compound Database and Library of derivatized PAHs and hydroxy PAHs enabled automated targeted quantification. Calibration curves were linear up to 2000 ng per mL for most compounds with mass accuracy below 1 ppm. Detection limits in both matrices ranged from 0.1 to 1 ng per mL based on replicate injections. The untargeted workflow identified additional PAH like compounds and xenobiotics in urine and plasma including cotinine and benzophenone. Low energy electron ionization spectra supported confirmation of molecular ions.

Benefits and Practical Applications

The combined targeted and untargeted approach allows comprehensive monitoring of persistent organic pollutants and metabolites in complex biological matrices. The high resolution accurate mass data provide reliable quantitation and rapid screening making this workflow suitable for biomonitoring studies and exposure assessment.

Future Trends and Opportunities

Enhancements in library coverage and data analysis algorithms will expand the range of detectable xenobiotics. Integration with advanced informatics and exposome research may enable more holistic assessments of human exposure to environmental contaminants. Continued development of low energy ionization methods could improve structural confirmation of unknowns.

Conclusion

The high resolution GC Q TOF platform delivers sensitive targeted quantification and broad untargeted screening of PAHs and hydroxylated metabolites in plasma and urine. This versatile workflow supports environmental health research and analytical toxicology applications.

References

Strickland MK Kang D Sithisarankul P Environ Health Perspect 1996 104 Suppl 5 927 932
Gupta P et al Journal of Analytical Toxicology 2015 39 5
Benowitz NL Epidemiol Rev 1996 18 2 188 204