Determination of Organochlorine Pesticides and Polychlorinated Biphenyls Using GC/MS/MS Operated in the MRM Mode

Significance of the Topic

Organochlorine pesticides and polychlorinated biphenyls (PCBs) are persistent environmental contaminants known for their toxicity and bioaccumulation. Reliable detection at trace levels is critical for environmental monitoring, regulatory compliance, and public health assessment.

Study Objectives and Overview

The objective of this study was to develop and validate a triple quadrupole GC/MS/MS method operated in Multiple Reaction Monitoring (MRM) mode for simultaneous quantitation of 20 organochlorine pesticides and 19 PCB congeners. A database of optimized MRM transitions and relative retention times was established to enable rapid method setup and enhance selectivity in complex matrices.

Methodology and Instrumentation

A nine‐point calibration (0.5–200 ppb) was prepared using a synthetic matrix containing EPA Method 625 target analytes. Internal standards and surrogates were added for quantitation and recovery assessment. Method validation included linearity, accuracy, precision, and estimation of method detection limits (MDLs) through replicate injections at low concentrations.

Used Instrumentation

• GC/MS/MS: Shimadzu GCMS‐TQ8040 triple quadrupole
• Column: Restek SH‐Rxi‐5 MS, 30 m × 0.25 mm × 0.25 µm
• Injection: Pulse splitless at 275 °C
• Carrier gas: Helium, constant linear velocity (43.5 cm/s)
• Oven program: 50 °C (0.5 min) → 265 °C (28 °C/min) → 285 °C (3 °C/min) → 330 °C (25 °C/min)
• MS source: 230 °C; interface: 290 °C; CID gas: Argon; MRM acquisition

Main Results and Discussion

Comparison of MRM and SIM showed a 5–10× improvement in sensitivity, with MRM MDLs well below those of EPA Method 608. Calibration curves exhibited excellent linearity (>0.995) and %RSD of response factors below 5%. Recovery studies at 10 and 20 ppb yielded 90–110% recovery with %RSD typically <5%. Internal and surrogate standards demonstrated stability with <6% RSD over multiple runs.

Benefits and Practical Applications

• Enhanced selectivity and reduced matrix interference without the need for dual‐column confirmation
• Lower detection limits enable trace‐level monitoring in environmental samples
• Simplified workflow and rapid method setup via optimized MRM database

Future Trends and Opportunities

Advances in MRM library expansion and automation will further streamline multi‐residue analysis. Integration with fast GC techniques and miniaturized extraction methods will increase throughput. The approach can be extended to emerging contaminants and complex environmental matrices.

Conclusion

The triple quadrupole GC/MS/MS MRM method on the Shimadzu GCMS‐TQ8040 provides a robust, sensitive, and selective alternative to EPA Method 608 for the determination of organochlorine pesticides and PCBs, achieving lower MDLs and reliable quantification in complex matrices.

References

1. Shimadzu Corporation, Technical Report C146‐E230, June 2013.
2. US EPA Method 608, CFR40 Part 136 Appendix A.
3. Restek, Technical Guide EVTG1648‐UNV, 2014.