title: Sorption-desorption of fipronil in some soils, as influenced by ionic strength, pH and temperature.
abstract: BACKGROUND
  The sorption-desorpion of fipronil insecticide is influenced by soil properties and variables such as pH, ionic strength, temperature, etc. A better understanding of soil properties and these variables in sorption-desorption processes by quantification of fipronil using liquid chromatography may help to optimise suitable soil management to reduce contamination of surface and groundwaters. In the present investigation, the sorption-desorption of fipronil was studied in some soils at varying concentrations, ionic strengths, temperatures and pH values, and IR specta of fipronil sorbed onto soils were studied.
  
  
  RESULTS
  The sorption of fipronil onto soils conformed to the Freundlich isotherm model. The sorption-desorption of fipronil varied with ionic strength in each of the soils. Sorption decreased but desorption increased with temperature. Sorption did not change with increasing pH, but for desorption there was no correlation. The cumulative desorption of fipronil from soil was significantly and inversely related to soil organic carbon content. IR spectra of sorbed fipronil showed the involvement of amino, nitrile, sulfone, chloro and fluoro groups and the pyrazole nucleus of the fipronil molecule.
  
  
  CONCLUSIONS
  The sorption of fipronil onto soils appeared to be a physical process with the involvement of hydrogen bonding. An increase in soil organic carbon may help to reduce desorption of fipronil. High-temperature regimes are more conducive to the desorption. © 2015 Society of Chemical Industry.
authors.affiliation: Department of Chemistry, College of Basic Sciences and Humanities, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India.
authors.forename: Anand
authors.initials: A
authors.lastname: Singh
authors.affiliation: Department of Chemistry, College of Basic Sciences and Humanities, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India.
authors.forename: Anjana
authors.initials: A
authors.lastname: Srivastava
authors.affiliation: Department of Soil Science, College of Agriculture, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India.
authors.forename: Prakash C
authors.initials: PC
authors.lastname: Srivastava
mesh_terms: D000327:Adsorption; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D007306:Insecticides / Q000737:chemistry*; D009994:Osmolar Concentration; D011720:Pyrazoles / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013696:Temperature
chemical_list: D007306:Insecticides; D011720:Pyrazoles; D012987:Soil; D012989:Soil Pollutants; C082360:fipronil
keywords: Freundlich isotherm; IR spectra; fipronil; soils; sorption-desorption