Studies on Formulation and Residue Analysis of Pesticides

Abstract

The dithizone method was applied for the determination of total mercury and organomercury in organomercury fungicides. Paper chromatography was applied for separation and identification of organomercury compounds in fungicide formulation. Gas chromatography with thermal conductivity detector was applied for the determination of D-D, EDB, DBCP, chloropicrin, DDVP, aldrin, dieldrin, chlorobenzilate, BHC isomers, nicotine sulfate, diazinon, heptachlor, VC-13, 2, 4-D ethyl ester, PCP, DBN, DCPA and PCNB in those formulation.An improved A. O. A. C. method by dithizone was applied for the determination of mercury residues in rice grains, fruits and tea leaves treated with organomercury fungicides. The amounts of mercury residues in raw rice grains treated with fungicide ranged from 0.04 to 0.84ppm, and influenced by mainly the lapse days after application. About 60% of mercury residues in raw rice grains was found in pollished grains and remaining 40% was in bran. The more high water solubility and hardly dissociated into ions the compounds has, the more uptake of mercury by rice plant from soil treated with those mercury compounds. Subsequently gas chromatography with electron capture detector was applied for the determination of organochlorine insecticides residues in various crops. The amounts of total BHC residues in raw rice grains treated with BHC dust ranged from 0.41 to 1.42ppm. Afterwards, from the similar purpose, on the relationship between the amounts of DDT and its derivatives residues in rice grains and apples and the history of application were examined under the field conditions.At finally, the biological concentration ratio (BCR) of the fourteen pesticides by fresh water fish, topmouth gudgeon were determined at the equilibrium condition under the continuous flow water system containing about 10ppb of those pesticides. These BCR obtained by this experiment were correlated to the octanol/water partition coefficient of individual compounds and inversely proportional to the water solubility. Therefore, it is able to predict the biological concentration potential of pesticide by means of these two physicochemical properties.