Behavior of sulfentrazone in ionic exchange resins, electrophoresis gels, and cation-saturated soils

Sulfentrazone persistence in soil requires many crop rotational restriction s. The sorption and mobility of sulfentrazone play an important role in its soil persistence. Thus, a series of laboratory experiments were conducted to mimic the soil properties of cation and anion exchange with different in termediates. The molecular characterization and ionization shift of sulfent razone from a neutral molecule to an anion were determined using a three-di mensional graphing technique and titration curve, respectively Sorption and mobility of 2.6 X 10(-5) M C-14-sulfentrazone were evaluated using a soil solution technique with ion exchange resins and polyacrylamide gel electrop horesis, respectively. Solution pH ranged from 4.0 to 7.4. As pH increased, sulfentrazone sorption to an anion resin increased and its sorption to a c ation resin decreased. Percent sulfentrazone in solution was pH-dependent a nd ranged between 0 to 18% and 54 to 88% for the anion and cation resins, r espectively. Mobility of sulfentrazone on a 20% polyacryalmide gel resulted in Rf values of +0.02 and +0.39 for pH of 4.0 and 7.4, respectively. A dou ble peak for sulfentrazone was detected in the polyacrylamide gel when the pH (6.0 and 6.8) was near the reported pKa of 6.56. There was no clear inte raction for the sorption of sulfentrazone at 1.0 mg kg(-1) to Congaree loam y sand or Decatur silty clay loam saturated with either calcium or potassiu m. Sulfentrazone behavior with the polyacrylamide electrophoresis gels and ion resins indicate the potential for this herbicide to occur as a polar or Zwitter ion. Sulfentrazone was adsorbed by potassium, calcium, and sodium saturated resins and subsequently desorbed using variable pH solutions. The level of sulfentrazone adsorption will vary among soil types and the amoun t of desorption into solution may be soil cation-dependent.