MULTIRESIDUE PESTICIDE ANALYSIS IN FRUITAND VEGETABLE COMMODITIES USING BOTH UPLC AND APGC ON A SINGLE MASS SPECTROMETER PLATFORM

Significance of the Topic

The widespread use of hundreds of pesticide formulations in agriculture demands robust analytical methods to ensure food safety and regulatory compliance. Multi-residue analysis detects and quantifies pesticide levels relative to maximum residue limits (MRLs) established by global authorities. Integrating fast, sensitive mass spectrometric techniques with streamlined sample preparation is critical for high-throughput testing in both industry and government surveillance programs.

Objectives and Overview of the Study

This study presents a unified workflow combining ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and atmospheric pressure gas chromatography mass spectrometry (APGC-MS/MS) on a single tandem quadrupole platform. Key goals include:

• Developing methods for ~200 pesticide residues per inlet with rapid switching between UPLC and APGC sources.
• Evaluating sensitivity, linearity, and precision across diverse fruit and vegetable matrices.
• Ensuring compliance with European SANTE/11945/2015 guidelines for pesticide residue analysis.

Instrumentation Used

The workflow employs a Xevo TQ-S micro triple quadrupole mass spectrometer equipped with a Universal Source for seamless interchange between:

• UPLC: ACQUITY UPLC H-Class system; BEH C18 column (2.1×100 mm, 1.7 µm); mobile phases water and methanol with 10 mM ammonium acetate; electrospray ionization (ESI+).
• APGC: Agilent 7890A GC with Rxi-5MS column (30 m×0.25 mm×0.25 µm); atmospheric pressure chemical ionization via proton transfer; CTC PAL autosampler.

Methodology and Sample Preparation

Samples of celery, lemon, corn, and kale were extracted using a QuEChERS protocol followed by dispersive SPE cleanup tailored to each matrix (MgSO4, PSA, GCB). Matrix-matched calibration standards (0.001–0.050 mg/kg) were prepared. Data acquisition used multiple reaction monitoring (MRM) with at least two transitions per analyte. UPLC calibrations were fitted linearly, while APGC data used quadratic fits in accordance with guidelines.

Main Results and Discussion

Both techniques achieved excellent performance:

• Detection at the default MRL of 0.010 mg/kg for >99% of analytes; many compounds detected at 0.001 mg/kg.
• Correlation coefficients (R2) ≥0.995 for the majority of calibration curves; residuals within ±20%.
• Precision with RSD <10% for >90% of compounds (UPLC and APGC), except APGC on kale (RSD <10% for >80%).
• Ion ratio deviations maintained within ±30% of reference values.
• Fast scanning provided ≥12 data points per peak, ensuring peak integrity in high-density MRM methods.

Benefits and Practical Applications

The combined UPLC and APGC workflow on a single instrument platform offers:

• Reduced instrument footprint and capital expenditure by avoiding separate LC and GC systems.
• Simplified method creation and maintenance through QuanPedia databases for MS, UPLC, and data processing methods.
• High throughput with rapid source switching (<30 min) supporting routine QA/QC and regulatory testing.
• Robust compliance with international guidelines, ensuring reliable surveillance of pesticide residues in complex food matrices.

Future Trends and Opportunities

Advancements may include:

• Integration of high-resolution and accurate-mass platforms to expand target and non-target screening capabilities.
• Enhanced automation of sample preparation and data processing for real-time monitoring.
• Miniaturized and field-deployable devices for on-site testing of produce.
• Application of machine learning for predictive analytics and method optimization across diverse analyte classes.

Conclusion

The presented multi-residue pesticide analysis successfully integrates UPLC-MS/MS and APGC-MS/MS on a single Xevo TQ-S micro system, delivering rapid, sensitive, and precise quantitation across fruit and vegetable commodities. The approach meets stringent SANTE criteria, streamlines laboratory workflows, and enhances the capacity for comprehensive food safety testing.

References

1. Shah D., McCall E., Cleland G. Single LC-MS/MS Method for Confirmation and Quantification of Over 400 Pesticides in a Complex Matrix Without Compromising Data Quality. Waters Application Note 720005559EN, 2016.
2. Kovalczuk T. et al. UPLC-MS/MS: A Novel Challenge in Multiresidue Pesticide Analysis in Food. Analytica Chimica Acta, 577, 2006.
3. Tienstra M. et al. Fast Gas Chromatographic Residue Analysis in Animal Feed Using Split Injection and APGC-MS/MS. J. Chrom. A, 1422, 2015.
4. Cherta L. et al. Application of GC-MS with APGC for Determination of Multiclass Pesticides in Fruits and Vegetables. J. Chrom. A, 1314, 2013.
5. European Commission. Guidance Document on Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed. SANTE/11945/2015, 2015.