Analysis of Residual Pesticides (No. 1: in Soybeans) Using Triple Quadrupole LC/MS/MS <LCMSTM-8060>

Significance of the Topic

Rapid and reliable detection of pesticide residues in food products is critical to ensure consumer safety and comply with increasingly stringent regulations. Soybeans, a key agricultural commodity used for human consumption and animal feed, can accumulate multiple pesticide residues. Integrating the QuEChERS sample preparation method with advanced triple quadrupole LC-MS/MS analysis addresses the need for high-throughput, sensitive, and accurate multi-residue screening in complex food matrices.

Objectives and Study Overview

The primary goal was to develop and validate a streamlined workflow for simultaneous quantification of 158 regulated pesticides in soybeans. The study evaluated recovery, repeatability, and matrix effects by spiking known pesticide standards into QuEChERS-treated soybean extracts, demonstrating method robustness for routine monitoring.

Methodology

Sample pretreatment followed the QuEChERS protocol: ground frozen soybean (5 g) was hydrated, extracted with acidified acetonitrile, and subjected to salt-based phase separation. The upper organic phase was cleaned using PSA, C18, GCB, and magnesium sulfate sorbents, yielding a final extract concentration of 0.5 g/mL. Matrix-matched calibration (10 ng/mL) assessed matrix suppression or enhancement effects.

Instrumentation Used

• Liquid Chromatograph: Shimadzu Nexera X2 with Shim-pack Scepter C18-120 column (100 × 2.1 mm, 3 µm)
• Mobile Phases: A) 5 mM ammonium formate, 0.02% acetic acid in water; B) 5 mM ammonium formate, 0.02% acetic acid in methanol; gradient from 5% to 97% B over 16 min
• Mass Spectrometer: Shimadzu LCMS-8060 triple quadrupole, ESI in positive/negative MRM mode
• Key Parameters: flow rate 0.3 mL/min; column temp. 40 °C; injection 1 µL; DL 200 °C; heat block 300 °C; nebulizing 3 L/min; drying 10 L/min; heating gas 10 L/min

Main Results and Discussion

Out of 158 target analytes, 156 compounds exhibited recoveries within the 70–120% acceptance range and relative standard deviations below 10%. Matrix effects were minimal for 98.7% of compounds, indicating effective cleanup and reliable quantitation. Representative MRM chromatograms showed clear separation and detection of analytes at 10 ng/mL levels in soybean extract.

Benefits and Practical Applications

• High throughput screening of multiple residues in a single run, reducing analysis time.
• Robust quantitation with excellent recovery and repeatability suitable for regulatory compliance.
• Minimal matrix interference enabling accurate low-level detection.
• Applicability to various food matrices beyond soybeans with minor adjustments.

Future Trends and Opportunities

Advancements in high-resolution mass spectrometry and automated sample preparation will further enhance sensitivity and broaden compound coverage. Integration of data-processing software and machine learning for spectral library matching can streamline identification in complex matrices. The method can be extended to emerging contaminants such as metabolites and degradation products.

Conclusion

The combination of QuEChERS extraction and triple quadrupole LC-MS/MS delivers a reliable, sensitive, and efficient approach for multi-residue pesticide analysis in soybeans. The validated workflow demonstrates excellent recovery, repeatability, and minimal matrix effects, making it well-suited for routine food safety testing.

References

1. Ministry of Health, Labour and Welfare: Testing Method of Agricultural Chemical Residues in Food, Feed Additives or Components of Animal Pharmaceuticals (PFSB/DFS Notification No. 1129002).