Organophosphate Pesticides

Even though a pesticide has been in wide use, it may not be free of extremely negative downsides. As awareness grows of the positive and negative impacts of certain pesticides, attention to regulation and monitoring often grows, sometimes extensively.

Through the 21st century, organophosphate pesticides were among some of the most widely used insecticides. In fact, thirty-six of them are currently registered with the EPA for use in the United States. Many organophosphate pesticides require frequent application because they are generally not persistent (1). Unfortunately, a dramatic downside to organophosphate pesticides is that this group of pesticides is now known to be poisonous to humans and animals alike, including birds, amphibians, and mammals (2). As a result of this knowledge, regulations for organophosphate pesticides are increasingly strict. For example, in 2022, the EPA introduced mandatory vegetative buffers between pesticide spraying and waterways for three organophosphates, requiring manufacturers to submit amended labels that included the new restrictions (3). And more recently, the EPA announced it will take accelerated action on high-risk uses for four organophosphate pesticides due to updated exposure assessments that revealed a more serious health risk (4). Within this type of changing awareness, accurate chemical analysis is critical for both organophosphate pesticide monitoring and to maintain the effectiveness of these types of regulatory initiatives for all pesticide monitoring.

There are several standard methods used for the determination of organophosphate pesticides, including EPA methods 8141B and 614. Most often, these methods prescribe the use of Gas Chromatography (GC) for the analysis of aqueous and solid samples. When using this technique for organophosphate analysis there are a few important considerations to keep in mind:

• Retention times of some analytes can increase with increasing concentrations in the injector, reducing reproducibility of results.
• Degradation is possible on reactive sites resulting in peak tailing or poor peak profile.
• Repeated injections can result in activity in the injector port creating matrix-effects.

To minimize these possibilities, be sure to:

• Regularly maintain your system to keep it free from contamination,
• Monitor for retention time shifts for samples that are highly contaminated, and
• Utilize high-quality reference materials throughout your analysis.
  

Remember, your instrument can be well maintained, but if you are not using the highest quality reference materials, you still risk poor data. When analyzing such highly regulated – and potentially dangerous – pesticides, turn to Analytichem for the highest quality reference materials you need so that you can have complete confidence in your results.

Continuing our discussion of pesticides leads us to Neonicotinoids, which we will describe in our next blog.

References:

1. Jepson, Paul C. “Pesticides, Uses and Effects of (I.B.3.B.iii. Organophosphates).” Encyclopedia of Biodiversity, Academic Press, 2001.
2. https://www.epa.gov/sites/default/files/documents/rmpp_6thed_ch5_organophosphates.pdf
3. https://cen.acs.org/environment/pesticides/Organophosphate-insecticides-restricted-protect-salmon/100/web/2022/07
   1. https://www.epa.gov/pesticides