Identification of Degradation Products of the Avicide 3-Chloro-p-toluidine Hydrochloride in Louisiana Rice Fields

An investigation of the migration of 3-chloro-p-toluidine hydrochloride (CPTH) on treated rice baits to soils in Louisiana rice fields was completed. The persistence of free CPTH in these soils was evaluated with field and laboratory experiments. These soils were also screened for the presence of CPTH degradation products. Soils treated with CPTH-fortified rice bait and aqueous solutions of CPTH were exposed under actual field conditions for a 13-day period. Control soil samples were also treated with CPTH and incubated under simulated field conditions in an environmental chamber. Soil samples were then screened for CPTH residues and degradation products by HPLC. Possible degradation products were identified with the assistance of LC/MS and GC/MS. The concentration of 2% CPTH on treated rice baits placed in Louisiana rice fields decreased by approximately 55% over 3 days. Several CPTH degradation products were detected in rice field soils, treated with an aqueous solution of CPTH, at concentrations too low for spectral identification. Multiple CPTH degradation products were detected in a laboratory soil metabolism study including the previously unreported compounds, cis- and trans-azo-3-chloro-p-toluidine (azo-CPT). Neither azo compound was detected in soils collected from fields that were treated with CPTH rice baits.