VALIDITY OF USING SOIL FORTIFICATION WITH DIELDRIN TO MEASURE SOLVENT EXTRACTION EFFICIENCY

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 airdried, treated with dieldrin-14C in pentane, and stored either in the airdried 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 airdried condition with various solvents. Extraction efficiencies of solvents were similar for the fieldand 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 orhexane-2-propanol gave similar recoveries (92 to 98%) from all soil treatments. Thusfortification of airdried soils with dieldrin should not be used for measuring true recovery rates from field samples extracted in the airdried state. © 1969, American Chemical Society. All rights reserved.