Reversed-phase chromatographic study of the binding of pesticides to humus extract

Abstract

The interaction of 18 pesticides with humus extract was studied by reversed-phase thin-layer chromatography and the effect of pH and the concentration of sodium chloride on the interaction was assessed. Interaction of six pesticides with humus extract was con®rmed in an aqueous system; the strength of interaction was highly dependent on the chemical structure of the pesticides. No signi®cant interaction was detected under acidic or alkaline conditions. Sodium chloride markedly decreased the strength of interaction, indicating the hydrophilic character of the interactive forces.

Pyrethrins and Piperonyl Butoxide Adsorption to Soil Organic Matter

“…In a similar RPTLC study by Cserhati and Forgacs, [19] there was no significant effect of humus extract on mobility of the pesticides atrazine, carboxin, and thiram. Water solubility of Pys and PBO is very low compared to atrazine, carboxin and thiram.…”

“…[5] A batch-equilibrium technique (amount of solute adsorbed by an adsorbent as a function of the equilibrium concentration of the solute) was used as described by Krohn [18] to study the adsorption isotherm of Pys and PBO to soil, while a reversed-phase thin-layer chromatography (RPTLC) technique as described by Cserhati and Forgacs [19] was used to study Pys and PBO mobility. Solutions of 10 ppm of Pys and 50 ppm of PBO were prepared to represent the recommended field application rate.…”

“…Plotting the linear form of the above equation as log q vs. (1/n log c þ log K d ) provides the slope of the regression line as 1/n and the intercept with the y-axe as log K d . RPTLC techniques developed to study binding and mobility of pesticides to humic substances [19] revealed that the R f values of Py-I, Py-II, and PBO decreased significantly (P < 0.05) as the amount of humic acid (the main component of the organic matter) increased (Fig. In addition, incorporating compost into the soil provides the nutrients (C, N, and Zn) needed to sustain vegetation (Table 3).…”

Sorption of endosulphan sulphate in soil organic matter

“…The solubility enhancement method [18,[21][22][23][24][25], dialysis bag technique [26][27][28], solid-phase micro-extraction (SPME) [29][30], reversephase separation techniques [31,32] and fluorescence quenching method [23,[33][34][35] are the techniques used to investigate the phase distribution of organic contaminants. The solubility enhancement method was used in the present study since it is possible to measure the bias in the method by measuring the solubility of the analyte in water.…”

The role of soil humic and fulvic acid in the sorption of endosulfan (alpha and beta)

“…[31] There are several methods reported in the literature that are used to estimate the partitioning of organic contaminants in soil organic matter. The solubility enhancement method [24,25,32,33], dialysis bag technique [34,35], solid-phase micro extraction (SPME) [36,37], reverse-phase separation [38,39] and fluorescence quenching [27,32] are used to investigate the phase distribution of organic contaminants.…”