Ultrasonic extraction and TLC determination of glyphosate in the spiked red soils

Pesticides that get into soil bind mostly to its solid phase by physical or chemical processes. In the valley of the Neretva River the use of herbicides, especially of glyphosate is widespread and sometimes uncontrolled. In this work ultrasonic solvent extraction (USE) followed by thin-layer chromatography (TLC) was applied for determining glyphosate presence in soil. The experiments were conducted with two characterised soil types. The impact of soil composition on extraction efficiency is discussed. Chemical analysis showed that soil 1 contained much more iron and aluminium oxides than soil 2, which was richer in humic substances. Low glyphosate efficiency (ca 44 % in both soils) could be attributed either to its binding to iron and aluminium oxides (soil 1), or to chemisorption on humic macromolecules (soil 2).