Simultaneous Determination of Pesticide Residues in Vegetable Extract by LC/MS/MS [LCMS™-8050]

Importance of the Topic

Accurate measurement of pesticide residues in agricultural products is a cornerstone of food safety monitoring and regulatory compliance. Complex sample matrices often cause signal suppression or enhancement in mass spectrometric analysis, posing challenges for quantification. Simplifying calibration while maintaining high accuracy and precision is essential for routine quality control and research applications.

Objectives and Study Overview

This study presents a method for the simultaneous determination of 89 pesticide residues in carrot extracts by liquid chromatography tandem mass spectrometry (LC-MS/MS) using an absolute calibration approach. The goal was to bypass labor-intensive matrix-matched calibration or standard addition methods while still achieving high recovery rates and reproducibility for trace-level analytes.

Methodology and Instrumentation

The sample preparation involved QuEChERS extraction of carrot puree followed by cleanup to obtain a matrix-matched extract. Calibration standards ranged from 0.1 to 50 ng/mL and were prepared in solvent. Key instrument conditions included:

• UHPLC: Nexera X2 system with Shim-pack Scepter C18-120 column (100×2.0 mm, 1.9 µm) at 40 °C
• Mobile phase: 5 mmol/L ammonium acetate in water (A) and methanol (B), gradient from 3% to 100% B over 26 minutes
• Flow rate: 0.4–0.6 mL/min, injection volume 5 µL
• Mass spectrometer: LCMS-8050 triple quadrupole with ESI in positive and negative modes
• Interface temperatures: DL 150 °C, interface 200 °C, block heater 500 °C; gas flows: nebulizer 2 L/min, drying 10 L/min, heating 10 L/min
• MRM acquisition with dwell times of 1–200 ms and transitions optimized for each pesticide

Main Results and Discussion

Spike-and-recovery tests at 1 ng/mL in carrot extract showed that 82 out of 89 pesticides achieved recoveries between 70% and 120%. Reproducibility (n=10) within 3% relative standard deviation was demonstrated for 70 compounds. Calibration curves for representative analytes exhibited excellent linearity across the tested concentration range. Extracted ion chromatograms confirmed clear, interference-free peaks and reliable quantitation.

Benefits and Practical Applications

The absolute calibration method simplifies routine analysis by eliminating the need for individual matrix-matched curves for each sample. High throughput screening of multiple pesticide residues in various produce matrices becomes more feasible, reducing labor and resource requirements. The approach supports compliance with regulatory guidelines and enhances laboratory efficiency in environmental, food safety, and industrial testing environments.

Future Trends and Opportunities

• Extension to diverse food and environmental matrices
• Integration with high-resolution mass spectrometry for non-target screening
• Automation of sample preparation and data processing workflows
• Use of chemometric tools and machine learning to predict and correct matrix effects

Conclusion

The combination of a Nexera X2 UHPLC system and LCMS-8050 triple quadrupole mass spectrometer enables reliable absolute calibration for the simultaneous quantification of a broad range of pesticides in carrot extracts. This method delivers high recoveries, excellent precision, and streamlined workflow, making it well suited for routine food safety monitoring.