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).
Interaction and binding of dissolved orthophosphate on insoluble complexes of marine humic substances and calcium, magnesium, iron and aluminium have been studied. The results pointed out that ...solubility of metal-humic and fulvic complexes increases as the pH of the suspension increases with strong phosphorus fixation at pH-values between 4 and 6. The possible mechanism of this binding involves formation of a complex association in which metal ions bound to the humic substances act as a bridge between humic macromolecules and phosphate anion.
The competitive sorption of phosphates and marine fulvic acids on mineral particles (sand, calcite, bentonite and hematite) has been studied under simulated estuarine conditions. Afterwards, the ...release and desorption of bound phosphates by solutions containing dissolved fulvic acids was determined. It was found out that due to the favorable sorption of fulvic acids onto minerals studied binding of phosphate was significantly decreased. Desorption experiments showed that fulvic acids, present at high concentration level, similar to that in interstitial water of an oxygenated sediment, increase phosphate desorption by 10-20%.
Reversed phase thin-layer chromatography (RP-TLC) in conjunction with video densitometry has been used for the quantitative determination of a six-component mixture of pesticides. Excellent ...separation of propham, chlorpropham, atrazine, diflubenzuron, tetramethrin and α-cypermethrin was achieved using the methanol/water solvent system (volume fraction of methanol, φ = 80%). Video densitometric quantification was validated for linearity, precision and detection limit. All results were satisfactory according to the validation requirements. The method was tested for the determination of pesticides from spiked soil using ultrasonic extraction with various solvents.
Interaction and binding of dissolved orthophosphate on insoluble complexes of marine humic substances and calcium, magnesium, iron and aluminium have been studied. The results pointed out that ...solubility of metalhumic and fulvic complexes increases as the pH of the suspension increases with strong phosphorus fixation at pH-values between 4 and 6. The possible mechanism of this binding involves formation of a complex association in which metal ions bound to the humic substances act as a bridge between humic macromolecules and phosphate anion.
Quantitative determination of combinations of the agrochemicals: atrazine, propham, chlorpropham, diflubenzuron, α-cypermethrin and tetramethrin from spiked soil is reported. Method involves ...ultrasonic extraction of agrochemicals with acetone, separation of samples by means of reverse-phase thin-layer chromatography and quantification by slit-scanning densitometry. Computer-assisted optimisation was used to select the optimum mobile phase composition. Apparent recoveries of agrochemicals from spiked soil were: 90.3±8.5 for chlorpropham, 79.3±10.3 for propham, 102±2.4 for atrazine, 100.6±5.4 for α-cypermethrin, 103.0±4.1 for tetramethrin and 98.3±4.9 for diflubenzuron.
Quantitative determination of combinations of the agrochemicals: atrazine, propham, chlorpropham, diflubenzuron, α-cypermethrin and tetramethrin from spiked soil is reported. Method involves ...ultrasonic extraction of agrochemicals with acctone, separation of samples by means of reverse-phase thin-layer chromatography and quantification by slit-scanning densitometry. Computer-assisted optimisation was used to select the optimum mobilc phase composition. Apparent recoveries of agrochemicals from spiked soil were: 90.3±8.5 for chlorpropham, 79.3±10.3 for propham, 102±2.4 for atrazine, 100.6±5.4 for α-cypermethrin, 103.0±4.1 for telramethrin and 98.3±4.9 for diflubenzuron.
