When subjected to conventional ashing (i.e. residue on ignition through use of a furnace and noble metal crucible), compounds ArC(=O)P(=O)Ar2 [Ar = aryl] give ash values of a few percent %w/w despite inorganic matter content being just a few thousand ppm at most. The crucibles are also attacked during the ashing procedure. When using a sulphated ash protocol instead, the latter difficulty does not occur, but values of a few percent %w/w are still obtained. If all of the organophosphorus was converted to inorganic phosphate by the test protocol, then one would expect higher ash values (10%w/w+) to be reported than those obtained. Can anyone explain why ashing and sulphated ashing of the above type of organophosphorus compounds are not giving sensible results, and the reason for crucible attack with ashing?
Twelve radiolabeled 14C-pesticides and herbicides were applied to the forearms of human subjects, and the urinary excretion of 14C was quantitated. Data obtained after iv dosing was used to correct the skin penetration data for incomplete urinary recovery. The data indicate that all the pesticides and herbicides tested are absorbed. The least absorbed was diquat, and the greatest absorption was found with carbaryl.
Article Percutaneous penetration of some pesticides and herbicides m man
I think this could be attributed to their thermal stability and flammability standards, hence organophosphorus compounds are used as flame retardant.
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