Interaction of diquat and paraquat with humic acid and the influence of salt concentration and pH on the strength of interaction

Cserháti, Tibor

doi:10.1007/bf00326348

Cited by 11 publications

(4 citation statements)

References 16 publications

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“…Selectivity studies were carried out to investigate the influence of surfactants and salts on the efficiency of the admicelles-based SPE for quats since these matrix components cause serious negative interference on the recoveries of most of the SPE methods described for quats. − With regard to surfactants, special attention was paid to alkylbenzenesulfonates (LAS) and nonionic surfactants (nonylphenol ethoxylate, NPE, was selected as a model) since they are the main surfactants present in environmental waters. The effect of electrolytes was investigated by using sodium chloride.…”

Section: Resultsmentioning

confidence: 99%

Evaluation and Optimization of an On-Line Admicelle-Based Extraction-Liquid Chromatography Approach for the Analysis of Ionic Organic Compounds

2004

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Admicelles-based solid-phase extraction (SPE) was on-line coupled with liquid chromatography/electrospray ionization/ion trap mass spectrometry, and it was proposed for the extraction of ionic organic compounds based on the formation of surfactant-analyte ion pairs. The approach was illustrated by studying the preconcentration of quaternary ammonium herbicides (quats) on sodium dodecyl sulfate (SDS) admicelles produced on alumina. Optimization of the parameters affecting SPE were studied on the basis that admicelles are dynamic entities in equilibrium with the aqueous phase. Some general guidelines could be established for method development from the results obtained. Factors influencing on-line operation were elucidated. On-line regeneration of the sorbent in each run was easily achieved by disruption of SDS admicelles with methanol and posterior coating of the alumina with SDS. The recovery of quats from drinking water samples were found quantitative for paraquat, diquat, and difenzoquat and above to 70% for chlormequat and mepiquat. Concentration factors of about 250, using sample volumes of 50 mL, were achieved. The detection limits ranged from 10 to 30 ng/L. The approach developed permits compliance with the directives of the European Community for drinking waters (100 ng/L) and goes deeply into the basis of solid-phase extractions that use surfactant-coated mineral oxide as sorbents.

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Section: Resultsmentioning

confidence: 99%

Evaluation and Optimization of an On-Line Admicelle-Based Extraction-Liquid Chromatography Approach for the Analysis of Ionic Organic Compounds

2004

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“…The curves tend to define a plateau suggesting the formation of a complete monolayer of quat molecules covering the adsorbent surface (isotherms belonging to subgroup II of the Giles classification). The cationic nature of quats governs its behavior, so the main sorption mechanism is a strong electrostatic interaction with the negatively charged surface of the adsorbents. , …”

Section: Resultsmentioning

confidence: 99%

“…The cationic nature of quats governs its behavior, so the main sorption mechanism is a strong electrostatic interactionwiththenegativelychargedsurfaceoftheadsorbents. 18,19 For both quats, on increasing crystallinity, an increase in sorption strength (K L ) but a decrease in sorption maximum capacity (X m ) was found (Table 3). Both PQ and DQ have higher sorption strength (K L ) on crystalline iron oxide coated quartz particles than on amorphous ones [(99 and 30) L • mmol -1 on Q Fec versus (41 and 16) L • mmol -1 on Q Fea for PQ and DQ, respectively], but the highest is for PQ [(99 or 41) L • mmol -1 ], which might be due to its strongest sorption strength.…”

Section: Paraquat and Diquat Sorption On Iron Oxide Coated Quartz Par...mentioning

confidence: 93%

Paraquat and Diquat Sorption on Iron Oxide Coated Quartz Particles and the Effect of Phosphates

et al. 2010

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The covering of quartz particles (Q) with Fe oxides provides high capacity sorption and immobilization of both paraquat (PQ) and diquat (DQ) as well as phosphates (P), that can be used to remediate contaminated environments due to their persistence. Both PQ and DQ have higher sorption strength on crystalline iron oxide coated quartz particles (QFec) than on amorphous iron oxides (QFea), but the highest is for PQ, which might be due to its strongest interaction. The increasing addition of P contributes to the increase of quat maximum sorption on iron oxide coated quartz particles, because the cosorption of P causes the surface charge to become more negative, facilitating the sorption of positively charged quats, but this happens in a different way for both quats. It was also seen that the formation of phosphate−quat complexes has a lower affinity than P by the coated quartz particles. The characteristics of the coated quartz particles would allow increased sorption of these quaternary ammonium herbicide contaminants.

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“…Thus, the binding of many inorganic ions such as cobalt,6 manganese,7 aluminium,8 iron,9 cadmium10 and other trace metals11 has been established. Organic pollutants such as polycyclic aromatic hydrocarbons,12 organochlorine pesticides,13 herbicides,14 algicides and fungicides15 can also be easily complexed with humic substances.…”

Section: Introductionmentioning

confidence: 99%

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

Cserháti

Forgács

2000

Pest Manag. Sci.

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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.

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Interaction of diquat and paraquat with humic acid and the influence of salt concentration and pH on the strength of interaction

Cited by 11 publications

References 16 publications

Evaluation and Optimization of an On-Line Admicelle-Based Extraction-Liquid Chromatography Approach for the Analysis of Ionic Organic Compounds

Evaluation and Optimization of an On-Line Admicelle-Based Extraction-Liquid Chromatography Approach for the Analysis of Ionic Organic Compounds

Paraquat and Diquat Sorption on Iron Oxide Coated Quartz Particles and the Effect of Phosphates

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

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