An impingement plate method to detect deposits of pyrethroid insecticides.
A silica gel impingement plate for monitoring pyrethroid deposits in environmentally sensitive areas is described. The plate is simple, commercially available, and inexpensive. A residue analysis method is given for deltamethrin deposits with 83.3% mean recovery and a minimum quantifiable limit of 0.005 microgram/plate. Pyrethroid deposits are strongly adsorbed to the silica gel, which prevents wash-off by rainfall and slows photodegradation. In two field experiments, deltamethrin was readily detected 3 weeks after direct spray applications at 6 and 10 g ai/ha. Deltamethrin dissipation on the plates was first-order with a half-life of 2.9-3.7 d. Photoisomers of deltamethrin were also detected on the plates and the ratio of photoisomers to deltamethrin increased over time. This ratio will indicate the age of deposits in monitoring situations.
Hill
B D
BD
Agriculture Canada Research Station, Lethbridge, Alberta.
Inaba
D J
DJ
D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D007306:Insecticides / Q000032:analysis*; D009570:Nitriles; D011722:Pyrethrins / Q000032:analysis*; D058428:Silica Gel; D012822:Silicon Dioxide; D014887:Weather
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; C017180:decamethrin; D058428:Silica Gel; D012822:Silicon Dioxide