LC-MS/MS Analysis of Emerging Food Contaminants

Importance of the Topic

The widespread use of glyphosate and related polar pesticides in agriculture has raised concerns about their residues in food and potential health effects. Reliable detection methods are essential for regulatory monitoring, quality control, and public health assessment. The development of sensitive, selective analytical techniques for underivatized glyphosate, AMPA, glufosinate, and MMPA addresses challenges related to their high polarity and low concentration in complex food matrices.

Objectives and Study Overview

This study evaluates a streamlined workflow combining QuPPe (Quick Polar Pesticides) extraction, mixed-mode liquid chromatography, differential mobility spectrometry (DMS), and tandem mass spectrometry (LC-DMS-MS/MS) to quantify glyphosate, AMPA, glufosinate, and MMPA in food. The goal is to achieve limits of quantitation (LOQs) of 100 µg/kg or lower, robust repeatability, and high identification confidence via multiple reaction monitoring.

Used Instrumentation

• ExionLC AD liquid chromatography system
• Acclaim Trinity Q1 mixed-mode column (100 × 3 mm, 3 µm)
• SCIEX QTRAP 6500 mass spectrometer with IonDrive Turbo V source
• SelexION® DMS cell for enhanced ion selection
• Analyst 1.6.3 and MultiQuant 3.0.2 software

Methodology

Sample Preparation:

• Homogenize 10 g of corn or soybean samples.
• QuPPe extraction using methanol with 1 % formic acid after water adjustment.
• Centrifugation followed by 10× dilution with LC-grade water to reduce matrix effects.

LC Conditions:

• Gradient of water containing 50 mM ammonium formate/formic acid (pH 2.9) and acetonitrile.
• Injection volume: 10 µL.

MS/MS Conditions:

• Negative electrospray ionization at 700 °C.
• SelexION® DMS with separation voltage (SV) 3800 V and compound-specific compensation voltages.
• Scheduled MRM with four transitions per analyte for quantifier and qualifier ions.

Main Results and Discussion

LC Method Selection:
The mixed-mode column at pH 2.9 exhibited optimal peak shapes, signal-to-noise ratios, and separation for scheduling MRM transitions.

Sensitivity and Repeatability:
LOQs of 100 µg/kg were achieved for all four analytes. At 10 ng/mL, intra-day precision yielded coefficients of variation between 2.4 % and 3.3 % over five injections.

Linearity and Accuracy:
Calibration curves from 1 to 1000 ng/mL showed correlation coefficients (r) > 0.999 with 1/x weighting. Recoveries ranged from 80 % to 120 % across levels.

DMS Enhancement:
SelexION® DMS removed matrix interferences, notably for AMPA and glufosinate, improving confidence in the detection of all four transitions per compound. Spiked corn and soy matrices confirmed clear identification under the SANTE/11945/2015 criteria.

Benefits and Practical Applications

• A derivatization-free workflow reduces sample preparation complexity and analysis time.
• High sensitivity and selectivity support routine monitoring of glyphosate and related metabolites in diverse food products.
• DMS integration enhances method robustness against matrix interferences.

Future Trends and Possibilities

Advances may include multiplexing polar contaminant panels, further automation of QuPPe extraction, and next-generation DMS devices for even greater selectivity. Integration with high-throughput platforms and data-driven screening will expand capabilities for food safety surveillance and regulatory compliance.

Conclusion

The presented LC-DMS-MS/MS approach, combined with QuPPe extraction, delivers a robust, sensitive, and selective method for underivatized glyphosate, AMPA, glufosinate, and MMPA in food matrices. LOQs of 100 µg/kg, excellent repeatability, and four-transition confirmation streamline routine pesticide residue analysis and meet stringent regulatory requirements.

References

• European Food Safety Authority. Conclusion on the peer review of glyphosate, EFSA Journal, 2015.
• IARC Monographs. Evaluation of five organophosphate pesticides and herbicides, Vol. 112, 2015.
• Battaglin WA et al. Glyphosate and transformation products in Midwestern streams, JAWRA 41(2):323–332, 2005.
• Vass A et al. Polar pesticide determination via HILIC and mixed-mode LC-MS/MS, Anal. Bioanal. Chem. 408:4857–4869, 2016.
• SANTE/11945/2015. Guidance on analytical quality control and method validation for pesticide residues, 2016.