Multi-residue Analysis of PAHs, PCBs and OCPs using an Agilent J&W FactorFour VF-35ms Column

Significance of the Topic

Multi-residue analysis enables simultaneous screening and quantification of diverse chemical classes—polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs)—in a single chromatography run. This approach reduces analysis time and costs while meeting the demand for comprehensive environmental monitoring of persistent pollutants.

Objectives and Study Overview

This study demonstrates an optimized gas chromatography–mass spectrometry (GC–MS) method using an Agilent J&W FactorFour VF-35ms column to separate and quantify 16 EPA-listed PAHs, 17 PCBs (including six EU marker congeners), and 24 common OCPs in one operation. Sample concentrations reflected realistic environmental ratios, with PAHs at ten times the level of PCBs and OCPs.

Methodology

• Column: VF-35ms, 30 m × 0.25 mm i.d., 0.25 µm film thickness.
• Oven program: 75 °C (1 min); 20 °C/min to 220 °C; 5 °C/min to 260 °C (2 min); 7 °C/min to 305 °C; 2 °C/min to 330 °C.
• Injection: 1 µL splitless at 100 °C (0.4 min), ramp to 300 °C, hold 15 min.
• Carrier gas: Helium at 1.0 mL/min (constant flow).
• Detection: Quadrupole MS with electron ionization in selected ion monitoring (SIM) mode.

Instrumentation

• Agilent GC system equipped with VF-35ms capillary column.
• Agilent quadrupole mass spectrometer: source at 230 °C, transfer line at 280 °C.

Main Results and Discussion

The VF-35ms column achieved baseline separation of 57 target analytes within 32.5 minutes. Key findings include:

• Two PAH isomer pairs (benzo[b]/benzo[k]fluoranthene and indeno[1,2,3-c,d]pyrene/dibenz[a,h]anthracene) coelute or share similar masses, requiring additional m/z channels for confirmation.
• PCB congeners PCB 138/PCB 163 and OCP pairs p,p′-DDD/o,p′-DDT and cis/trans-heptachlor epoxide exhibit identical primary ions, necessitating secondary ions for reliable identification.
• The method maintains resolution and sensitivity for analytes at different concentration levels typical of environmental samples.

Benefits and Practical Applications

• High-throughput screening of multiple persistent organic pollutants in a single run.
• Cost and time efficiency by consolidating analyte groups.
• Robust column performance supports trace-level environmental and industrial analysis.

Future Trends and Potential Applications

• Integration with high-resolution mass spectrometry for enhanced selectivity and resolving power.
• Development of shorter, high-temperature-tolerant columns for faster analyses.
• Automation and field-portable GC–MS systems for on-site environmental monitoring.
• Application expansion to food safety, forensic toxicology, and metabolic studies.

Conclusion

This optimized GC–MS method on the VF-35ms column provides a rapid, reliable solution for multi-residue analysis of PAHs, PCBs, and OCPs, improving analytical throughput without compromising separation quality.

References

• Anon (2005) Report of the Joint FAO/WHO Expert Committee on Food Additives, Sixty-fourth meeting, 8–17 February 2005, Rome, Italy.
• U.S. EPA. Information on PCBs: EPA Quick Facts. http://www.epa.gov/epawaste/hazard/tsd/pcbs/pubs/about.htm
• University of Illinois at Chicago School of Public Health. What are PCBs? http://www.uic.edu/sph/glakes/pcb/whatarepcbs.htm
• AKAction. Organochlorine Pesticide Fact Sheet. http://www.akaction.org/fact_sheets/Organochlorine_Pesticide_Fact_Sheet.pdf