Phosphamidon residues

A study of phosphamidon residues (3) in soil which was again made up of the litter layer plus soil to a depth 15 cm showed a rapid loss of the insecticide with the last measurable deposit (level of detection 0.025 ppm) being recorded at 4 days post spray and non-detectable levels after 8 days post spray. This particular study compared the deposits in both coniferous and deciduous areas and similar results were found in each location, thus indicating that litter from coniferous and deciduous trees acted as a common base for the insecticide deposit. 

Endosulfan and phosphamidon residues were detected by cobalt acetate and o-tolidine on TLC plates with the sensitivity of 10 pg (160c). 

In measurements of the fate of phosphamidon applied as an aqueous solution on spruce trees (Picea glauca spp) (3) it was shown that while there were measurable residues on the trees a rapid loss of the chemical occured. The rapid decrease in concentration (ppm wt/wt) was partially attributed to a dilution effect from the rapidly expanding new foliage. 

Sundaram (4) found that, due to the geometry of the needle fir (Abies balsamea) acted as a better receptor of phosphamidon than spruce foliage. The fir collected about 75% more insecticide than the spruce. In comparing the relative amounts of the cis and Trans isomers, it was found that the Trans isomer was preferentially absorbed into the foliage while the cis form remains on the surface. The surface residue is then more rapidly lost by physical and metabolic processes. 

A similar behavior pattern is found in the insecticide residues in the litter-soil complex partly as a result of needle fall fenitrothion residues persist for an extended period (up to one year). Phosphamidon and aminocarb disappear very quickly. 

The insecticides that have a longer residual life (DDT and to a limited extent phosphamidon) do so because they are absorbed into the waxy layer of the cuticle and are protected from the environment. This protection from the environment may also remove the insecticide as a biological hazard. 

The acetonitrile layers are mixed and poured into another separatory funnel. In cases of dimethoate, Dasanit, phosphamidon and DDVP poisonings, the three acetonitrile fractions are combined and evaporated to dryness, and the residue is taken up in one milliliter of acetone. Further extraction of acetonitrile is avoided as this results in appreciable loss of pesticides. The acetonitrile layer is diluted with water to ten times of its original volume. Twenty-five ml. of saturated sodium sulfate solution is added to this solution and extracted three times with twenty-five milliliter-portions of n-hexane previously saturated with distilled water. The separated n-hexane layers are combined and then concentrated to two milliliters on a warm water bath. 

Phosphamidon (99, 2-chloro-2-ethylcarbamyl-l-methyl-vinyl dimethyl phosphate) has a broad spectrum of activity against biting and sucking pests and spider mites.54 A cyclic enol phosphate is prepared from 100. They are heptenophos (101, Hostaquick ), a systematic insecticide, and acaricide (anti-tick and anti-mite agent) with a short residual effect.54... 

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