TLC For Pesticide Testing

We had some unwanted myclobutnail contamination recently and it was a real pain in the ass to clean up; I spent 2 weeks decontaminating my membrane system and boiling my solvent. Now we screen material that comes in.

We’ve started to piece material from many cultivators and this poses an issue of not knowing who is the source is problematic since it can cost $200 per pesticide test.

To prevent ballooning testing costs, a field pesticide test for myclobutanil seems like something that could be helpful. Has anyone had any success with this or even attempted it? The goal is to be able to detect (not quanitify) down to ~0.5-1 ppm of myclo. This seems possible but I’m curious about visualizing it.


Maybe start here?


The “fungal spore assay” seems like it should do the trick…

4.4. Detection of pesticides

The detectability of pesticides was tested with the following systems:

  • UV lamp at 254 nm HF (254) ― Silica gel 60 HF254
  • o-Tolidine and potassium iodide (o- TKI) ― Silica gel 60
  • p-nitrobenzene-fluoroborate (NBFB) ― Silica gel 60
  • p-dimethylamino benzaldehyde (p-DB) ― Aluminium oxide G
  • Silver nitrate & UV exposition (AgUV) ― Aluminium oxide G
  • Photosynthesis inhibition (Hill) ― Silica gel 60
  • Fungi-spore inhibition (Aspergillus niger) (FAN) ― Silica gel 60
  • Fungi-spore inhibition (Penicillium cyclopium) (FPC) ― Silica gel 60
  • Enzyme inhibition with cow liver extract and β-naphthyl acetate substrate (EβNA) ― Silica gel 60
  • Enzyme inhibition with pig or horse blood serum and acetylthiocholine iodide substrate (EAcI) ― Silica gel 60

The fungi spore inhibition [FAN] and [FPC] methods provided the best specificity. They sensitively detect only fungicides at the usual concentration level of pesticide residues (0.01– 5 mg/kg). Therefore they are very suitable TLC detection methods for residue analysis.


That would be nice but I don’t think there are any field tests that will get anywhere near the sensitivity you want.

For 1ppm of myclo youd probably need an LCMS

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1mg/kg is 1ppm

Should be noted that test is a FUNCTIONAL test (is there anything in the solution that prevents growth of fungus) – one would also require a already defined TLC that you know the elution of myclobutanil on in order to give it specificity. An intentional spike at high concentrations is going to be the quickest way to develop that part.


My main concern is myclo since I’m in a semi-humid area.

Maybe giving a triazole test kit a try could work, there’s some with a uv lamp kit made for benzotriazole, which fluoresces yellow. Benzotriazole also seems to make a coordination polymer with copper; perhaps a new and interesting way to remediate myclo.

Yep, hence: “Functional test for fungicides…”

Should. As a professed non-chemist I stopped worrying about detection once I saw the list they had covered…figured at least one would work for almost any analyte.

Especially after the biology based test I could actually wrap my head around.