Azide and Ethylenethiourea Mobility in Soils
1974
Helling, Charles S. | Thompson, Susan M.
A masking technique was developed for visualizing nonradioactive compounds on soil thin-layer chromatographic plates. To determine azide mobility, leached plates were sprayed with a kaolinite slurry in 95% ethanol, air-dried, and resprayed with 2% Fe(NO₃)₃ in 5% HNO₃. The average RF of azide in four mineral soils was 0.87, and in a muck 0.21; it is thus quite mobile in most soils. The form of azide (NaN₃, KN₃, or KN₃ + K₂CO₃) did not affect mobility. 2-Imidazolidinethione (ethylenethiourea, or ETU), a degradation product of ethylenebis (dithiocarbamate) fungicides, was evaluated after masking with kaolinite + alumina (1:2), sprayed onto soil plates in 95% ethanol. Nitroprusside and Grote's reagents were useful chromogenic reagents. Mobility was also determined by autoradiography of [¹⁴C]ETU; average RF's for four mineral soils ranged from 0.83 to 1.00, decreasing to 0.61 in a muck. Although weakly adsorbed from solution, ETU is immobilized by drying the soil before leaching. 2-Imidazolidone (ethyleneurea) and possibly sulfur were detected in soil incubated 7 days with ETU.
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