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Determination of 1,2-Dibromoethane (EDB) in Field Soils: Implications for Volatile Organic Compounds

Dep. of Soil and Water, The Connecticut Agric. Exp. Stn., 123 Huntington St., Box 1106, New Haven, CT 06504;

S. M. Steinberg

Global Geochemistry Corp., 6919 Eton Ave., Canoga Park, CA 91303.

^* Corresponding author.

ABSTRACT

A method is described for determining 1,2-dibromoethane (EDB) in soils previously fumigated with EDB. The procedure involves extraction of soil with methanol at 75°C for 24 h in a sealed vial, followed by gas chromatographic analysis of the extract. Reproducibility of the method was demonstrated using replicated samples by separate analysts, and the detection limit was 1.8 µg kg^–1. Acetone and acetonitrile were as efficient. Other published methods for determining volatile organic compounds (VOCs) in soils and sediments gave very low recoveries relative to the above method. A purge and trap method (EPA Method 8240) released less than 10% EDB, even at higher temperatures and longer purge times than recommended. Thermal desorption from soil columns with a stream of N₂ at 100 to 200°C resulted in decomposition rather than desorption of EDB. By contrast, a freshly added spike was recovered quantitatively at these temperatures. Two other methods, sonication-extraction and Soxhlet extraction, which are commonly used for nonvolatile and semivolatile compounds in soil, also gave low recoveries of EDB from the fumigated field soils. The vigorous conditions needed to extract a labile compound like EDB are consistent with our previous findings that EDB in the field samples is trapped in soil micropores from which diffusive release is slow.

Key Words: Pesticide residue analysis • Volatile organic compounds • Purge and trap method • Sorption

Contribution from the Dep. of Soil and Water, The Connecticut Agric. Exp. Stn., New Haven, CT.

Received for publication March 20, 1987.