Determination of anionic polar pesticides and oxyhalides in beer and strawberry samples using IC-HRAM-MS

Importance of the topic

The reliable detection of polar pesticides, their metabolites, and disinfection by-products in food and beverages is vital for ensuring consumer safety and meeting increasingly stringent regulatory limits. Anion-exchange chromatography coupled with high-resolution accurate-mass mass spectrometry (IC-HRAM-MS) offers selectivity and sensitivity for ionic analytes that are challenging for conventional LC- or GC-MS approaches.

Objectives and study overview

This study presents a unified IC-HRAM-MS method to quantify 14 anionic polar pesticides (including glyphosate, glufosinate, and their metabolites), perchlorate, and oxyhalide by-products (chlorite, chlorate, bromate) in complex matrices (beer, strawberries) within a 15-minute run time. Method performance, limits of detection (LODs), and applicability to real samples are demonstrated.

Methodology

A Dionex Integrion HPIC system with eluent generation (15–75 mM KOH gradient), high-pressure degassing, and suppressed conductivity detection was coupled in-line to a Q Exactive Focus hybrid quadrupole-Orbitrap via an IC-MS interface for acetonitrile makeup. Key operating parameters:

• Columns: Dionex IonPac AG19-4 µm guard (2 × 50 mm) and AS19-4 µm separator (2 × 250 mm) at 40 °C.
• Eluent: KOH gradient from 15 mM to 75 mM over 10 min, back to 15 mM by 11.5 min.
• Flow rates: IC 0.45 mL/min; makeup solvent (acetonitrile) 0.23 mL/min.
• Conductivity detection: ASRS 300 suppressor in external water mode (0.5 mL/min regenerant).
• MS: HESI II negative-ion mode, full scan 60–750 m/z (30k resolution), and t-SIM for quantifiers at 15k resolution.
• Sample preparation: QuPPe extraction for strawberries; simple dilution (10–100×) for beer.

Used Instrumentation

• Dionex Integrion RFIC HPIC system with EGC 500 KOH eluent cartridge, CR-ATC 600 trap, high-pressure degasser.
• Dionex IonPac AG19 and AS19 columns.
• Dionex AS-AP autosampler with cooling.
• Q Exactive Focus MS with HESI II probe.
• SRD-10 suppressor regenerant detector for safety interlock.

Main results and discussion

Calibration in the 50–2000 ng/L range yielded LODs of 0.1–0.5 µg/L for oxyhalides, bromide, and perchlorate, and 0.05–1 µg/L for polar pesticides. Strawberry extracts revealed bromide (~100 ng/L) without detectable bromate or perchlorate. Beer samples (seven brands) showed glyphosate in a rice-barley beer, gluten-free sorghum beer, and non-alcoholic barley beer at sub-µg/L levels; recoveries ranged 78–95%.

Benefits and practical applications

This single-run IC-HRAM-MS approach streamlines monitoring of a broad panel of ionic contaminants, reducing the need for multiple analyses or derivatization steps. It supports food safety labs and regulatory agencies by delivering rapid, accurate, and trace-level determinations in diverse matrices.

Future trends and potential applications

Advances in high-pressure RFIC and Orbitrap mass analyzers will drive further reductions in analysis time and improved sensitivity. Expanded analyte panels (e.g., emerging metabolites, novel disinfection by-products) and fully automated sample-to-result workflows are anticipated, enabling real-time quality control in food production.

Conclusion

An integrated IC-HRAM-MS method was established for 18 anionic compounds in food matrices. The 15-minute analysis met sensitivity, selectivity, and accuracy requirements for regulatory compliance. Demonstrated success in beer and strawberry samples underscores its utility for routine food-safety monitoring.

References

1. Christison T., Gerardo L., Beck J., Rohrer J. Determination of anionic polar pesticides and oxyhalides in beer and strawberry samples using IC-HRAM-MS. Thermo Fisher Scientific Application Note 72765, 2018.
2. PubChem. National Institutes of Health. https://pubchem.ncbi.nlm.nih.gov/
3. ChemSpider. Royal Society of Chemistry. https://www.chemspider.com/
4. US EPA. Pesticide Sales database. https://www.epa.gov/pesticides/chem_search
5. European Food Safety Authority (EFSA). EFSA Explains: Glyphosate Risk Assessment. 2015.
6. Thermo Fisher Scientific. TN175: Configuring the Dionex Integrion HPIC System for High-Pressure RFIC. 2017.
7. Thermo Fisher Scientific. AN661: Rapid Analysis of Polar Pesticides in Foods by IC-MS. 2017.
8. Thermo Fisher Scientific. AN533: Perchlorate in Infant Formula by IC-ESI-MS/MS. 2017.
9. ASTM D1193-99e1. Standard Specification for Reagent Water. ASTM International.