Multiple Tools for Demanding Needs: Trace Detection of Organochlorine Pesticides by Agilent 7000E and 7010C GC/MS/MS

Importance of the Topic

Persistent organochlorine pesticides pose long-term threats to ecosystems and human health due to their stability and bioaccumulation. Sensitive and reliable detection at ultratrace levels is essential for environmental monitoring, regulatory compliance, and risk assessment.

Objectives and Study Overview

This work compares two Agilent triple quadrupole GC/MS/MS systems (7000E and 7010C) for the trace-level analysis of 20 common organochlorine pesticides (OCPs). The aim was to assess detection limits, dynamic range, and overall robustness using dynamic multiple reaction monitoring (dMRM) mode.

Methodology and Instrumentation

The study employed an Agilent 8890 GC fitted with either:

• Agilent 7000E TQ with extractor ion source
• Agilent 7010C TQ with high-efficiency ion source

Key experimental details:

• Column: 30 m × 0.25 mm × 0.25 µm DB-8270D-UI
• Injection: multimode inlet in solvent vent mode, volumes 1–3 µL
• Carrier gas: helium at 1.25 mL/min constant flow
• Oven program: 40 °C hold, ramp to 260 °C, to 280 °C, then to 320 °C
• Standards: OCP mixtures in dichloromethane, concentration ranges 0.01–1000 ppb (7000E) and 0.01–500 ppb (7010C)
• Acquisition: dMRM for enhanced selectivity and sensitivity

Main Results and Discussion

Both systems achieved detection of most OCPs at 10 ppt with 1 µL injection and gain of 10. Notable findings:

• Dieldrin and endrin, traditionally challenging compounds, were detected at 25 ppt on the 7000E with good signal-to-noise ratios.
• Increasing injection volume from 1 µL to 3 µL provided only marginal improvements on the 7010C, indicating 1 µL is sufficient for routine trace analysis.
• Lower gain settings (gain 1 and 5) on the 7000E still allowed ppt-level detection for most analytes, demonstrating flexibility in dynamic range versus sensitivity.
• The 7010C delivered the lowest detectable levels for several OCPs, while the 7000E offered a broader linear dynamic range up to ppm levels.

Benefits and Practical Applications

The combined features of high sensitivity, selectivity, and wide dynamic range make these GC/TQ configurations suitable for:

• Environmental water and soil analysis
• Food safety and residue testing
• Regulatory compliance monitoring
• Quality assurance in industrial contexts

Future Trends and Applications

Advances may include integration with automated sample preparation (SPME, SPE), on-line coupling for real-time monitoring, and further refinement of dMRM scheduling to accommodate even larger analyte panels with minimal cycle times.

Conclusion

Agilent 7000E and 7010C GC/TQ systems both deliver robust trace-level performance for organochlorine pesticide analysis. The 7010C excels at achieving ultralow detection limits, while the 7000E provides extended dynamic range. Method flexibility allows tailoring injection volume and gain settings to meet diverse analytical requirements.

References

1 Mrema E., et al. Persistent organochlorinated pesticides and mechanisms of their toxicity. Toxicology 307 (2013) 74–88.