Extraction and Analytical Techniques for Pesticides in Soil, Sediment, and Water

Development of the concepts presented in previous chapters presumes that pesticide content determined accurately for a sample truly represents the sampled medium. Thus, the sample must be representative and the pesticide content in the sample mu'st be identified and measured accurately. In the past, less attention was devoted to selection of analytical and sampling techniques than to the other aspects of experimental design. Often, the methods employed were evaluated inadequately or were applied directly without first determining their applicability under local conditions. \\Then the processes of pesticide sorption and solvation are better understood, it will be possible to design sampling extraction and analytical procedures on a theoretical basis. Until that time, methodological design and evaluation that is largely empirical is the best means of circumventing this lack of knowledge and compensating for the effect of unknown or ill-defined relationships. However, the empirically derived and tested technique must be clearly defined and is valid only within the range of the original experimental conditions. Thus, methods should not be extrapolated beyond the limits imposed by these conditions without further experimentation. In general, this is the criterion most violated by pesticide researchers. This paper presents a general overview of the subject of pesticide extraction and analysis of soil, water, and sediment samples without elaborating on specific procedures. The common pesticidal names are used throughout 'the body of this paper, and for the convenience of the reader, the chemical names are listed in tables in the Appendix.