Federal Researchers Develop Rapid Test for Detecting Over 100 Pesticides on Marijuana Plants
- Federal researchers developed a rapid screening method using DART-MS that can detect 108 out of 113 pesticides tested on marijuana plant material, enabling faster identification of contaminated samples before detailed lab analysis.
- The method was effective on both pesticide standards and real cannabis samples spiked or treated with pesticides, demonstrating practical applicability in detecting pesticide residues on actual plants.
- Positive-ionization mode at 350°C was the most effective condition, detecting 93% of pesticides, while the technique offers rapid mass-spectral results with minimal sample preparation compared to conventional methods.
- The screening tool is qualitative and intended to complement, not replace, quantitative laboratory testing, potentially serving as a frontline monitoring step to identify samples needing more extensive analysis.
Federal researchers have developed a rapid screening method capable of detecting 108 of 113 pesticides tested on marijuana plant material, potentially providing a faster way to identify contaminated samples before more extensive laboratory analysis.
The study, published in the Journal of Agricultural and Food Chemistry, was conducted by Megan I. Chambers and Walter B. Wilson of the National Institute of Standards and Technology (NIST). It was published online in late August and appeared in the journal’s September issue.
Researchers developed a method using direct analysis in real time mass spectrometry, known as DART-MS, to screen for pesticides commonly associated with cannabis cultivation. Of the 113 pesticides evaluated, the technique detected 108, or about 96%, under at least one of the conditions tested.
Positive-ionization mode proved particularly effective, detecting 105 pesticides, or 93% of those examined. Negative-ionization mode detected 77, or 68%. Researchers found that positive-ionization mode with a gas temperature of 350 degrees Celsius produced the strongest overall results.
The researchers did not limit the experiment to pesticide standards. They also tested the technique on cannabis plant materials that had been deliberately spiked with pesticides and on plants treated with pesticides during cultivation, demonstrating that the approach could detect numerous pesticide residues in actual plant samples.
According to the researchers, one of the potential advantages of DART-MS is speed. The technique can generate substantial mass-spectral information in a matter of seconds and does not require the extensive sample preparation associated with many conventional analytical methods.
The authors said the method could potentially be used at the front end of a pesticide-testing process, including for monitoring residues on plant leaves or examining possible pesticide drift from neighboring agricultural fields. It could also help laboratories determine which samples warrant more extensive testing.
The researchers emphasized that the method is currently a qualitative screening tool rather than a replacement for quantitative laboratory testing. A positive screening result could instead inform subsequent analysis designed to determine how much of a particular pesticide is present.
Researchers said the study appears to be the first to use DART-MS for multiresidue pesticide detection on marijuana plant material. They added that incorporating a quantitative component into the technique in the future appears feasible.