Part One. Development of analytical methods for the determination of selected 'organic pesticides'. Part Two. DDT and its metabolites in soil and air at an agricultural site near South Haven, Michigan: Determination and implications.

摘要

Part one of this research was conducted to develop a multiple pesticide analytical residue method for the determination of the "Organic Pesticides", Nicotine, Pyrethrum, Rotenone, and Warfarin. This research determined the optimum detection and chromatographic conditions for the analytical determination of these four pesticides in a multiresidue scheme. The desire to achieve a multiresidue method that was efficient (accurate and precise) and economical yielded a method that did not meet desired lower limit of detection. The four pesticides had physical properties quite different from each other which required the method to change pH from neutral to basic and then to an acidic pH. The second part of the method development work involved pesticides that did not have individual residue analytical methods that were previously published. The pesticides analyzed were alpha-terthienyl, azadiractin, ryanodine, and veratridine. The chemical and physical properties of these four pesticides had many similarities and thus facilitated their simultaneous extraction, separation, and detection.;The second part of this research involved analysis of air and soil samples to determine the spatial distribution of DDT and it's metabolites (sum of DDT) in Southwestern Michigan. Historically, levels of DDT have been elevated in this geographical region. The levels were found to be easily quantified with gas chromatography (GC) during the sampling period from April 1998 to August 1998. Historically this site has been under extensive fruit and vegetable farming and received high inputs of DDT in the past. The research supports the postulate that the elevated levels of DDT in the area are due to volatilization from the soil. The soil samples from the site had DDT levels elevated above outlying areas. The ratio of DDT to its metabolites also supports the view that the DDT was from past spraying before the 1973 ban in the United State of DDT. Calculations were determined from the residue data to estimate the time for the soil to dissipate the residues and it was found to range from a few years to thousands of years.