Detecting Pesticide Residues in Dry Herbs Using Advanced Lab Techniques

Jim Crocker
25th June, 2024

Detecting Pesticide Residues in Dry Herbs Using Advanced Lab Techniques

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at the University of Brasília developed accurate methods to detect EBDC fungicides and ETU in dry herbs
  • The study found that 19.4% of the 103 dry herb samples tested positive for EBDC residues, but no ETU residues were detected
  • The findings highlight the need for monitoring to prevent illegal pesticide use in herbs, ensuring consumer safety
Dithiocarbamates are a class of fungicides widely used in agriculture due to their broad-spectrum activity and cost-effectiveness. However, their frequent detection in the environment and food has raised concerns about potential health risks. A recent study conducted by the University of Brasília[1] aimed to develop and validate methods for determining ethylene-bis-dithiocarbamate (EBDC) fungicides and their degradation product ethylenethiourea (ETU) in dry herbs used for food and medicinal purposes. The study focused on mancozeb, a commonly used EBDC fungicide. Researchers validated a method involving complexation with EDTA, derivatization, and extraction using dimethyl sulfate in acetonitrile, followed by purification with primary secondary amine (PSA). For ETU, L-cysteine hydrochloride monohydrate was added to samples before extraction and purification. A pesticide-free blend of seven herbs was used as a control to ensure the accuracy of the methods. The methods demonstrated high recoveries (79-113% for EBDC and 81-109% for ETU) and precision (<20% repeatability and intermediate precision). The limits of quantification were 0.03 mg/kg for EBDC and ETU, with detection limits set at 0.01 mg/kg. The study analyzed 103 samples of 33 different dry herbs and found that 19.4% were positive for EBDC residues, while no ETU residues were detected. This suggests potential illegal use or cross-contamination of pesticides, as no dithiocarbamates are registered for use on these herbs in Brazil. Although the detected EBDC levels did not indicate a health risk, the findings highlight the need for monitoring to prevent illicit pesticide use, especially in herbs intended for therapeutic purposes. The methods developed in this study build upon previous research into the detection of dithiocarbamates in various food matrices. For instance, earlier studies have described methods for determining EBDCs in fruits and vegetables[2] and in beer, fruit juice, and malt samples[3]. These methods also involved the transformation of EBDCs into methylated derivatives followed by extraction and detection using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The current study extends these methodologies to dry herbs, demonstrating their applicability across different types of food and medicinal products. The rapid and efficient detection methods validated in this study are crucial for ensuring food safety and preventing the illegal use of pesticides. By providing reliable techniques for monitoring EBDC and ETU residues, the research supports regulatory efforts to safeguard consumer health. The findings also underscore the importance of continuous surveillance of pesticide residues in various food products to address potential contamination issues and ensure compliance with safety standards. In conclusion, the study conducted by the University of Brasília successfully validated methods for detecting EBDC fungicides and their degradation product ETU in dry herbs. These methods offer high accuracy and precision, contributing to the broader effort of monitoring and regulating pesticide residues in food and medicinal products. The research highlights the need for ongoing vigilance to prevent illegal pesticide use and protect consumer health.

HerbsBiochemPlant Science

References

Main Study

1) Determination of ethylene-bis-dithiocarbamates and their degradation product ethylenethiourea in dry herbs by UHPLC-MS/MS.

Published 24th June, 2024

https://doi.org/10.1039/d4ay00597j

Related Studies

2) Simple and rapid method for the determination of ethylenebisdithiocarbamate fungicides in fruits and vegetables using liquid chromatography with tandem mass spectrometry.

https://doi.org/10.1007/s00216-008-2346-8

3) A rapid and sensitive analysis of dithiocarbamate fungicides using modified QuEChERS method and liquid chromatography-tandem mass spectrometry.

https://doi.org/10.1584/jpestics.D17-025


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