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pesticide extraction from polymeric seed coating
Posted: Thu Jul 03, 2014 7:49 pm
by fatskhan
I am trying to determine the applied pesticide concentration in artificially coated seeds. Have tried various methods unsuccessfully. Cannot get complete removal of the coating or complete dissolution into organic solvent. Anyone with experience in this field?Any help will be much appreciated
Re: pesticide extraction from polymeric seed coating
Posted: Fri Jul 04, 2014 7:05 pm
by Don Shelly
It would help us to know the composition of the seed coating, the name of the pesticide and which techniques have you tried?
Re: pesticide extraction from polymeric seed coating
Posted: Tue Jul 08, 2014 2:21 pm
by fatskhan
Hi
The seed coating consists of a polymer (most likely polyvinyl alcohol), mica and pigment. The details are a bit hazy, because the companies are afraid to reveal the exact components of the coating. Currently looking for clothianidin, imidacloprid and abamectin.
I have done some solvent solubility tests. Most of the coating seems to be water soluble. I have tried lowering the pH to increase solubility and this seems to be working. Acetone seems to extract the pigment from the coating, but there is quite a lot of the solid coating left on the seeds. Methanol does not work at all. There is limited dissolution with acetonitrile.
The water appears to dissolve/swell the polymer. Next step ought to be solvent extraction. Or perhaps a modified quechers extraction so that I can extract the pesticides and transfer to organic solvent suited to GCMS analysis. (Except for abamectin, which I will have to remove via clean-up [thinking SPE]).
Thanking you for any suggestions
Re: pesticide extraction from polymeric seed coating
Posted: Tue Jul 08, 2014 2:58 pm
by Don Shelly
You might try dissolving in warm water with agitation. Extract and clean-up using a buffered QuEChERS. Use matrix matched calibration.
Re: pesticide extraction from polymeric seed coating
Posted: Thu Jul 10, 2014 12:11 pm
by fatskhan
Great idea. Thanks
Re: pesticide extraction from polymeric seed coating
Posted: Thu Jul 10, 2014 5:59 pm
by Consumer Products Guy
What about a high-speed homogenizer? That should pulverize everything, allow the solvent to reach the analyte.
Re: pesticide extraction from polymeric seed coating
Posted: Mon Aug 04, 2014 7:16 pm
by fatskhan
Thank you for all your suggestions. I swelled the polymer with warm water and agitation. Then used a quechers extraction. In the process of validation now. Getting beautiful fairly clean chromatograms
Re: pesticide extraction from polymeric seed coating
Posted: Mon Aug 04, 2014 9:21 pm
by Don Shelly
Thank you for all your suggestions. I swelled the polymer with warm water and agitation. Then used a quechers extraction. In the process of validation now. Getting beautiful fairly clean chromatograms
Glad it's working for you. Thanks for the feedback.
Don