Analysis for Organic Pesticides in Aquatic Environments

Abstract

The detection of organic pesticides in aquatic environments represents an unique analytical problem. It is unique in the context that specificity is required under extremely sensitive conditions as opposed to gross analysis for trace organics in water. First, there is the problem of pesticide identity. Second, direct measurement is not feasible because of sensitivity and specificity requirements. Extraction, concentration, and cleanup techniques must be employed prior to qualitative analysis and quantification. Third, natural waters may contain such organic interferences as aromatic and aliphatic compounds from industrial waste waters, and naturally occurring colored compounds. These impurities are often present in concentrations greater than the pesticide. Two objectives are offered herein: (1) a brief critique of extraction, cleanup, identification, and quantification techniques is given in order to highlight limitations fallacies, and pitfalls, and (2) a model system for the recovery, separation, and confirmation of organophosphate pesticides, oxons, and their hydrolysis products. This model system provides the basic needs of pesticide methodology; namely, simplicity and minimum sample handling. The problems of recovery from water by liquid-liquid extraction, separation by gas-liquid chromatography, and subsequent confirmation by micro-ultraviolet absorption spectrophotometry are discussed.

Adsorption of Cd, Cu, Ni, Pb and Zn on Sphagnum peat from solutions with low metal concentrations

“…The electronegativity of the element. Table 2 Second-order rate constants for adsorption of metals onto peat Table 4 summarizes the above-mentioned characteristics of the metals used in this study as well as the corresponding stability constants for metal-humic acid [26] metal-fulvic acid complexes [27]. The series of affinities from the result of this study is in good agreement with experimentally obtained stabilisation constants for metal-humic/fulvic acids complexes.…”

Characterisation of Odorous Compounds and Emissions from Slurries Produced from Weaner Pigs Fed Dry Feed and Liquid Diets

“…This can be attributed to the reduced slurry viscosity from the diets containing more water. Biological activity is usually a positive function of substrate concentration, but high viscosity can restrict access to the nutrients (Faust and Hunter 1976).…”

Chemical speciation and bioavailability of lead and cadmium in an aquatic system polluted by sewage discharges

“…Sewage effluents are rich in dissolved organic matter, hence strong complexation ofPb with organic ligands or chelates forming non-labile species is envisaged. The argument is supplemented by the observations made by Faust and Hunter (1971) which suggest high concentrations of both particulate and dissolved organic maHer in sewage effluents. Although particulate Pb is absent at site 3, 100% of it is in dissolved form and only 13% is bioavailable; thus revealing its tendency to associate with inorganic suspended solids (Hem, 1976;Gadde and Laitinen, 1974).…”