Rapid determination of DDT and related compounds in soils via carbon skeleton gas chromatography-mass spectrometry.

The levels of DDT and related compounds in soil samples from an apple orchard have been determined. Extraction of residues was achieved by cyclic steam extraction and by conventional solvent extraction methods allowing comparison of the two methods. Determination of the organochlorine residues present in the extracts was performed by gas-liquid chromatography-electron-capture detection and by carbon skeleton gas chromatograph-mass spectrometry. Excellent agreement between the two determination techniques was achieved. Prior to application of p,p'-DDT, a value of approximately 0.4 ppm was obtained for Delta DDT in the soil. The major component of this total was DDE. After spraying the apple trees with technical grade, p,p'-DDT, Delta DDT for the soil rose to 0.6 ppm. This increase was due to translocation of p,p'-DDT from the trees.