Validity of using soil fortification with dieldrin to measure solvent extraction efficiency

Abstract

Four different types of soil with 13 to 18% moisture content when field-collected were treated in that condition with an aqueous suspension of dieldrin-14C (field soils). Samples of the same soils were air-dried, treated with dieldrin-14C in pentane, and stored either in the air-dried state (dry soil) or after addition of 20% water (moist soil). All samples were stored for 6 to 8 months and subsequently extracted in the air-dried condition with various solvents. Extraction efficiencies of solvents were similar for the field and moist soils; much higher recoveries were obtained from the dry soils. Addition of 20% water to the soils immediately before extraction with 1 -to-1 hexane-acetone or hexane-2-propanol gave similar recoveries (92 to 98%) from all soil treatments. Thus fortification of airdried soils with dieldrin should not be used for measuring true recovery rates from field samples extracted in the air-dried state.

Extraction of [14C]glyphosate from Saskatchewan soils

“…The assessment of extraction procedures for glyphosate from soil is difficult given the complex and timeconsuming cleanup and detection procedures. Several analysts have used 14C-labeled pesticides to compare extraction procedures following various equilibration periods (Chiba and Morley, 1968;Saha et al, 1969;Lichtenstein et al, 1977). Thus, the use of [14C]glyphosate would give an accurate and simple means of comparing recoveries of the herbicide from fortified soils using various solvent systems, extraction procedures, and aging periods.…”

Comparison of solvent systems for the extraction of atrazine, benzoylprop, flamprop, and trifluralin from weathered field soils

“…Under such conditions, a particular procedure may indicate that over 90% of a specific residue is being recovered; however, this may not necessarily mean that the same extraction efficiency will be achieved from field samples treated several months previously (Hamaker et al, 1966; Chiba and Morley, 1968;Saha et al, 1969).…”

“…When a pesticide residue remains in contact with field soils for extended periods, a phenomenon known as aging, or weathering, occurs which renders the pesticide residue more resistant to solvent extraction (Hamaker et al, 1966; Chiba and Morley, 1968;Chiba, 1969;Saha et al, 1969;Mattson et al, 1970). This resistance to extraction has been considered to result from an increased adsorption to soil colloids and a diffusion into the interior of humic acid particles (Hamaker et al, 1966;Chiba, 1969;Adams, 1973;Khan, 1973).…”

Sorption‐desorption kinetics of some organochlorine insecticides in silt‐water suspensions

“…It has been suggested 28 · 29 that solute molecules can be trapped in cages formed by Η-bonds in the polymeric humin network. From the work of Saha et al 23 it can be concluded that the recoveries of dieldrin, applied to moist field soil, are reduced when the soil is air-dried before extraction with acetone + hexane (1:1). This indicates that the humin structure is not so rigid as has been assumed.…”