Polar pesticides in honey

Significance of the Topic

Honey production is a growing global industry requiring strict quality control to ensure food safety. Polar herbicides such as glyphosate glufosinate and their metabolites can contaminate honey via environmental exposure or hive treatments. Regulators have set maximum residue limits for these compounds to protect consumers. Analytical methods capable of accurately detecting trace levels of anionic pesticides in a complex sugar-rich matrix are vital for routine monitoring and compliance.

Objectives and Study Overview

This work aims to develop validate and implement an automated sample to result workflow for multi residue analysis of polar anionic pesticides in honey. The approach employs ion chromatography coupled with triple quadrupole mass spectrometry to directly quantify glyphosate aminomethylphosphonic acid (AMPA) and glufosinate without derivatization. Key goals include reducing matrix interference extending instrument uptime and achieving detection limits below regulatory thresholds.

Methodology and Instrumentation

Sample Preparation

• Commercial and local honey samples were diluted with ultrapure water to a concentration of 100 g per liter
• After filtration through a 0.2 micron polymer filter samples were injected directly without further cleanup

Chromatographic and Mass Spectrometric Conditions

• An ion chromatography system with electrolytic KOH eluent generation and a polymeric anion exchange column separated target analytes at elevated pH
• A suppressor regenerated in external water mode converted eluent to deionized water before detection
• A timed switching valve was employed to divert the high concentration sugar fraction away from the mass spectrometer between 2.5 and 5.5 minutes
• An inline isopropanol make-up flow improved electrospray desolvation
• A triple quadrupole mass spectrometer operated in negative mode selected reaction monitoring for each analyte

Instrumental Setup

• High performance ion chromatograph with KOH eluent generator
• Polymeric anion exchange column with guard
• Electrolytically regenerated suppressor
• Triple quadrupole mass spectrometer with HESI source
• Automated detector control and data processing software
• Ultrapure water system and high purity reagents

Main Results and Discussion

The method achieved linear calibration from 0.1 to 5 micrograms per liter with correlation coefficients above 0.9997. Limits of detection and quantification for all analytes were below 0.2 micrograms per liter corresponding to honey levels well under the EU MRL of 0.05 milligrams per kilogram. Inline sugar elimination minimized matrix buildup on the ion source and maintained stable signal over extended sequences. Analysis of various honey types demonstrated recoveries within acceptable ranges and identified samples with elevated glyphosate exceeding the permitted limit.

Benefits and Practical Applications

• Direct analysis of complex matrices without derivatization simplifies sample workflow
• Electrolytically regenerated suppressor ensures continuous desalting and robust chromatography
• Automated matrix diversion extends instrument uptime and reduces maintenance requirements
• Triple quadrupole detection provides the sensitivity and selectivity needed for trace level monitoring
• Compatibility with routine control laboratories facilitates high sample throughput

Future Trends and Potential Applications

Advances in high resolution accurate mass spectrometry may further improve specificity and expand the range of detectable polar residues. Integration of isotopically labeled standards could enhance quantitation in complex matrices. Coupling with rapid sample preprocessing or online dilution techniques may allow direct screening of other foodstuffs. The modular design of modern ion chromatography platforms will support multi class pesticide monitoring and emerging contaminants in diverse samples.

Conclusion

An integrated IC MS MS workflow was established for reliable quantitation of glyphosate AMPA and glufosinate in honey. The approach offers low detection limits robust performance against matrix effects and compliance with regulatory requirements. Automated sugar removal and electrolytic eluent suppression streamline the analytical sequence and support routine residue surveillance in apiculture products.

References

1. FAO Codex Alimentarius standard on honey 2017
2. Silva LR Videira R Monteiro AP Valentão P Andrade PB Microchemical Journal 2009 73 73–77
3. Escuredo O Huidobro JF Simal-Lozano J Sancho MT Food Chemistry 2014 146 290–296
4. FAO FAOSTAT production statistics for 2018
5. EU Regulation on maximum residue limits in honey 2013
6. ISO 8466-2 Water quality Calibration and evaluation of analytical methods 2001