Improving the Sensitivity, Ruggedness, and Accuracy of Pesticide Analysis

Importance of the Topic

The reliable detection of trace-level pesticides and endocrine disruptors in food and environmental samples is essential for public health, regulatory compliance, and quality control. Analytical methods that combine sensitivity, breadth of coverage, and operational robustness enable laboratories to efficiently screen large numbers of compounds in complex matrices while minimizing downtime and maintenance.

Objectives and Overview of the Study

This work aimed to develop a single‐run, multi‐residue GC/MS protocol capable of:

• Screening for over 900 GC‐amenable pesticides and endocrine disruptors.
• Quantifying target compounds at concentrations below 10 ppb.
• Completing the analysis in under 25 minutes.
• Reducing instrument maintenance and improving data accuracy.

Methodology

A combined synchronous SIM/Scan acquisition was employed on an Agilent 7890/5975 GC/MS system equipped with Trace Ion Detection. Key elements of the workflow included:

• Programmable temperature vaporization (PTV) inlet for 10 µL large‐volume injections to push detection limits below 10 ppb.
• QuickSwap backflush interface to remove heavy matrix components through the inlet split port immediately after each run.
• HP-5MSi capillary column (15 m × 0.25 mm id × 0.25 µm) operated under constant flow.
• Deconvolution Reporting Software (DRS) based on AMDIS for automated component extraction and spectral matching.
• Synchronous SIM to maximize sensitivity for target compounds alongside full‐scan data for non‐target screening.

Used Instrumentation

• Agilent 7890 GC coupled to a 5975C MSD with Trace Ion Detection.
• Agilent 7683 autosampler with PTV inlet capable of large‐volume injections.
• QuickSwap MSD interface with makeup gas for backflush operations.
• HP-5MSi capillary column.
• AMDIS/Deconvolution Reporting Software integrated with ChemStation.

Main Results and Discussion

Implementing backflushing between runs maintained stable retention times and baselines over dozens of 10 µL injections, whereas non-backflushed conditions led to retention shifts and elevated noise after only three injections. The DRS approach successfully deconvoluted coeluting species in QuEChERS extracts of lettuce, extracting clean spectra for library matching and quantification. In a typical 23-minute run, 54 pesticides were identified at 10 ppb in lettuce in under two minutes of data review, and up to 927 compounds could be screened in a single sequence.

Benefits and Practical Applications

• Improved sensitivity for trace-level pesticides without extensive sample cleanup.
• Reduced column and source maintenance through automated backflush.
• Comprehensive screening and accurate quantification in one run, enhancing laboratory throughput.
• Robust performance suitable for routine QA/QC, regulatory monitoring, and research studies.

Future Trends and Potential Applications

Advances in data processing algorithms and expanded spectral libraries will further enhance detection of emerging contaminants. Integration with high‐resolution mass spectrometry and automated sample preparation techniques could push detection limits lower and broaden method applicability to novel matrices such as soils, water, and complex biological samples. Ongoing improvements in instrument ruggedness and software intelligence are expected to streamline workflows and support field‐deployable analytical platforms.

Conclusion

The presented GC/MS approach demonstrates a practical and efficient solution for multi‐residue pesticide analysis at sub-10 ppb levels. By combining large‐volume injection, backflush technology, synchronous SIM/Scan acquisition, and deconvolution software, laboratories can achieve high sensitivity, broad screening capability, and long-term operational stability in a single, rapid analytical run.