Optimizing Clean-Up Methods to Detect Pesticides and Toxins in Medicinal Herbs

Jenn Hoskins
12th July, 2024

Optimizing Clean-Up Methods to Detect Pesticides and Toxins in Medicinal Herbs

This study developed a new analytical method to simultaneously detect pesticides and mycotoxins in the chemically distinct and complex matrices of lemon balm (Melissa officinalis, left) and high mallow (Malva sylvestris, right).

Composite: Natural Science News / CC BY. [Sources]
Adapted from photos by:

Key Findings

  • Researchers from the Federal University of Santa Maria developed a method to detect over 160 pesticide and mycotoxin residues in medicinal plants
  • The method showed high accuracy and precision for detecting 157 pesticide residues and mycotoxins in Melissa officinalis and 152 in Malva sylvestris
  • The study found significant contamination in real samples from Southern Brazil, proving the method's practical use for routine monitoring
The use of medicinal herbs has seen a significant rise, driven by their potential health benefits and natural origins. However, the presence of pesticide residues and mycotoxins in these herbs has raised substantial concerns among regulatory agencies. To address this issue, researchers from the Federal University of Santa Maria have developed and optimized a QuEChERS method for the simultaneous determination of over 160 pesticide and mycotoxin residues in complex medicinal plant matrices using LC-TQ-MS/MS[1]. This study aims to enhance the safety and quality of medicinal herbs by providing a sensitive, accurate, and precise analytical method. The study's primary objective was to create a reliable method for detecting a wide range of pesticide and mycotoxin residues in medicinal plants. These contaminants can pose serious health risks, including carcinogenic, genotoxic, and reproductive effects, as highlighted by previous studies[2]. The challenge lies in the complex nature of medicinal plant matrices, which contain numerous naturally occurring substances that can interfere with the detection process. To achieve this, the researchers conducted a comprehensive comparison of clean-up procedures and other parameters. The validation procedure followed the guidelines of SANTE 11312/2021, ensuring the method's accuracy and precision. The study evaluated two specific medicinal plants: Melissa officinalis L. and Malva sylvestris L. These plants were chosen due to their common use in traditional medicine and their potential contamination risks. The results showed that more polar analytes, such as acephate, methamidophos, and omethoate, exhibited a higher negative matrix effect in both M. officinalis and M. sylvestris. Conversely, molecules like spirodiclofen showed varying effects, with a 24% signal enhancement in M. officinalis and a 46% signal suppression in M. sylvestris. These findings indicate that a representative matrix-matched calibration is crucial for accurate quantification of the analytes. The method demonstrated satisfactory accuracy and precision for 157 pesticide residues and mycotoxins in M. officinalis and for 152 molecules in M. sylvestris, according to SANTE 11312/2021 guidelines. The limits of quantification (LOQs) were achieved at 10 µg kg-1 for 117 pesticides in M. officinalis and 99 pesticides in M. sylvestris. Among the mycotoxins, all four aflatoxins (B1, B2, G1, and G2) presented LOQs of 5 µg kg-1, and ochratoxin A had an LOQ of 10 µg kg-1 in M. officinalis. The same LOQ values were shown for these mycotoxins in M. sylvestris, except for aflatoxin B2 and ochratoxin A, which had LOQs of 20 µg kg-1. The study's findings align with previous research that underscores the importance of monitoring contaminants in herbal medicines. For instance, a study revealed that pesticides were present in 88% of herbal medicine samples, with more than half containing pesticides over the European Pharmacopoeia limit[2]. Additionally, the presence of mycotoxins, such as aflatoxins, in food and medicinal plants poses significant health risks, as evidenced by historical data on aflatoxin toxicity[3]. Moreover, the application of this method was assessed through the analysis of forty-two real samples from Southern Brazil, a region where no previous study on mycotoxin and pesticide contamination in medicinal herbs had been conducted. The results identified the presence of imidacloprid in M. officinalis and methyl pirimiphos in M. sylvestris, highlighting the method's practical utility for routine monitoring. In conclusion, this study provides a robust analytical tool for detecting pesticide and mycotoxin residues in medicinal plants. By ensuring the safety and efficacy of these herbs, the method supports better risk assessment and control in food safety. This work not only addresses a significant public health concern but also lays the foundation for future research in the field.

HerbsMedicineBiochem

References

Main Study

1) Comprehensive assessment of clean-up strategies for optimizing an analytical multi-method to determine pesticides and mycotoxins in Brazilian medicinal herbs using QuEChERS-LC-TQ-MS/MS.

Published 11th July, 2024

https://doi.org/10.1039/d4ay00599f

Related Studies

2) Detection and risk assessments of multi-pesticides in 1771 cultivated herbal medicines by LC/MS-MS and GC/MS-MS.

https://doi.org/10.1016/j.chemosphere.2020.127477

3) Aflatoxins: History, Significant Milestones, Recent Data on Their Toxicity and Ways to Mitigation.

https://doi.org/10.3390/toxins13060399


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