In 1874 Othmar Ziedlert a German chemist was working on the synthesis and characterization of substituted aromatic hydrocarbons. In the process of his work he synthesized dichloro-diphenyl-trichloro-ethane commonly known as DDT. It was not until 1930 that its use as an insecticide was detected by Paul Muller who found that it was effective against potato beetles (Leptinotarsal declineata) and clothes moths, (Tineola besselliella ) (Dunlap 1981). Pure DDT is a white crystalline solid with a melting point of 109 C, and a vapor pressure of 0.025mPa at 20 C. Technical grade DDT is a white amorphous powder, consisting of a mixture of active 4,4'-DDT(65-80%), inactive 2,4'-DDT(14-21%), up to 4% DDD (1,1'-(2,2-dichloroethylidene) bis (4-chlorobenzene), and traces of 2,2'DDT. This mixture readily dissolves in xylene and tetraline (600 g/L), moderately dissolves in mineral oil and kerosene (50-80g/L), and is practically insoluble in water (1.2ug/ml) (Elvers et al. 1989).



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