The world of pesticide analysis is a virtual minefield littered with pitfalls and challenges to navigate but careful navigation can result in quality data that accurately identifies and quantitates the pesticide content found in your samples. Among the challenges in pesticide analysis are location, crop and seasonal-specific use of pesticides. Making the challenges even more complex are novel pesticides, some unidentified, which are being developed and implemented every day across the globe. Because of this, the list of pesticides that need to be monitored is ever-growing.
Guidance for different regions can provide us with direction for which pesticides to target but several questions quickly arise: What compounds do I look for and when do I look for them? How many pesticides will be in my sample? How do I know that I am not missing compounds? And, finally, are my methods capable of capturing all of the pesticides present in the sample? Because of these uncertainties, the need for combined targeted and non-targeted methodologies is quickly becoming a reality in sample assessment for pesticides.
What Happened to Ten Little Pesticides
I had the opportunity to interact with some of the world’s top pesticide chemists at the Pesticide symposium last month in Prague, CZ. Poor me, I know! Besides having a wonderful time exploring the city’s many architectural and edible treasures, I was able to gather some important insight from pesticide analysts who are experiencing analytical challenges relating to pesticide analysis in their labs on a daily basis. One particular experience I would like to share with our blog faithful is a sad story about what happened to ten little pesticides.
10 Little Pesticides*
10 little pesticides were in the sample,
1 didn’t get extracted and stayed behind,
And 1 degraded, poor little guy,
How many pesticides were in the extract?
8 little pesticides were in the extract,
One was lost in the clean-up without a trace,
And one was diverted to the LC waste,
How many pesticides made it to the MS?
6 little pesticides made it to the MS,
One didn’t ionize in electrospray,
And one would have but got suppressed,
How many pesticides reached the detector?
4 little pesticides reached the detector,
Like what you are learning?
One was too little to be detected,
And one was masked, hidden, neglected,
How many pesticides could be identified?
2 little pesticides could be identified,
1 was not in the database,
And 1 was finally found!
*Courtesy Dr. Katerina Maštovská, Associate Scientific Director, Nutritional Chemistry and Food Safety, Covance Laboratories.
Limiting Outside Influences on Data
The story in the above poem highlights the difficulties most of us have experienced when analyzing pesticides in the lab. Outside influences other than data interpretations can have dramatic effects on the accuracy of your data output. Of course, being highly skilled, highly motivated and acutely aware analytical chemists, we can attempt to limit the influence of our system and methodology on the data that we produce by taking the following steps:
- Careful inspection of components and routine elements of your system prior to analysis
- Implementing instrument performance protocols and benchmarks
- Careful evaluations of control sample data
- Documenting routine maintenance and troubleshooting
- Inclusion of non-targeted methodologies to existing targeted methodologies
No matter what challenges you are experiencing in pesticide analysis or the inspiration for improving your analysis, it is important that 1) you should share experience with other analysts to gain insight and avoid repeating mistakes made by others, and 2) continually scrutinize system performance and methods to ensure you are obtaining the most accurate sample assessment from the analysis. The efforts we employ to ensure quality analysis ensure the protection of our environment, our food supply, and, most importantly, people everywhere.
As Winston Churchill said (and slightly modified by me): “Success consists of going from failure to failure without loss of pesticides enthusiasm!”
Applications for the Analysis of Pesticides
I went through our database of applications and compiled some of the current ones that would be of interest to analytical chemists involved in this type of analysis:
- Application Note: Detection of OrganochlorinePesticides by GC-ECD Following U.S. EPA Method 8081 (downloadable PDF)
- Application Note: Analysis of Dithiocarbamate Pesticides by GC-MS (downloadable PDF)
- Application Note: Consolidated GC-MS/MS Analysis of OCPs, PAHs, and PCBs in Environmental Samples (downloadable PDF)
- Application Note: Rapid Solution for Screening and Quantitating Targeted and Non-Targeted Pesticides in Water using the Exactive Orbitrap LC/MS (downloadable PDF)
- Application Note: Analysis of Triazine Pesticides in Drinking Water Using LC-MS/MS (EPA Method 536.0) (downloadable PDF)
If pesticide analysis is of interest to your laboratory, we would like to hear about your thoughts and experiences.