Quantitative Analysis of Pesticides in QuEChERs Extracts Using APGC/MS/MS

Importance of the Topic

Monitoring pesticide residues at trace levels is essential to ensure food safety and regulatory compliance. Farmers use hundreds of pesticides, and analytical labs must screen for multiple compounds in fruits and vegetables within tight timeframes. Advanced methods that achieve low detection limits and high throughput are critical for consumer protection and quality assurance.

Objectives and Overview of the Study

This work evaluates atmospheric pressure gas chromatography tandem mass spectrometry (APGC/MS/MS) for quantitative analysis of GC-amenable pesticide residues in QuEChERS extracts from strawberry, pear, spinach, and tomato samples. Goals include demonstrating sensitivity, limits of detection, and linearity across a range of pesticide standards using APGC/MS/MS.

Methodology

Samples were prepared according to the DisQuE QuEChERS protocol, extracting matrices with acetonitrile. A nine-point calibration (0–50 ng/mL) was spiked into each matrix extract, and a deuterated internal standard (chrysene-d12) at 2 ng/mL was used for injection normalization. Triplicate analyses were performed for each calibration level. Two MRM transitions per pesticide—quantifier and qualifier—were monitored, focusing on 20 compounds known for fragmentation challenges under electron ionization.

Instrumentation

APGC was conducted on a Waters Xevo TQ-S mass spectrometer coupled to an APGC ionization source and a 7890A gas chromatograph. The interchangeable ion source supports both GC and LC workflows, enabling APGC, UPLC, or ACQUITY UPC2 to be paired with a single MS platform.

Main Results and Discussion

Calibration curves for all 20 pesticides exhibited excellent linearity (R2 > 0.99) over 0.05–50 ng/mL, with residuals within 20 %. Limits of detection ranged from 0.01 to 0.5 ng/mL. Minimal matrix effects were observed across sample types, with consistent retention times and peak shapes. The production of abundant [M+H]+ ions under APGC improved selectivity and sensitivity compared to traditional electron ionization methods.

Benefits and Practical Applications

The soft ionization offered by APGC enhances parent ion signals, simplifying the development of specific and sensitive MRM transitions for pesticides. A universal ionization source streamlines laboratory workflows by consolidating GC and LC analyses on one instrument, increasing throughput and resource utilization.

Future Trends and Potential Applications

Future developments may extend APGC/MS/MS methods to a broader range of pesticide chemistries and sample matrices. Integration with high-throughput automated sample preparation and coupling with supercritical fluid chromatography could further enhance screening capacity and reduce analysis times.

Conclusion

APGC/MS/MS on the Waters Xevo TQ-S platform delivers robust, sensitive, and accurate quantification of trace-level pesticide residues in fruit and vegetable extracts. The method meets stringent regulatory requirements and supports efficient multi-residue screening in diverse matrices.

Reference

Waters Corporation. Quantitative Analysis of Pesticides in QuEChERS Extracts Using APGC/MS/MS. August 2013.