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A method is described for the simultaneous determination of the experimental insecticide nifluridide (N-(2-amino-3-nitro-5-(trifluoromethyl)phenyl)- 2,2,3,3-tetrafluoropropanamide) and its cyclized product, EL-919 (7-nitro-2-(l,l,2,2-tetrafluoroethyl)- 5-(trifluoromethyl)benzimidazole), in water. Both compounds are extracted by passage of up to 500 mL water through two Sep-Pak C18 cartridges joined in series. The extraction is automated by using vacuum. The compounds are eluted from the cartridges with acetonitrile. Both compounds are then separated and measured by high pressure liquid chromatography with UV detection at 235 nm. Recoveries were 91.2-97.1% nifluridide and 82.7-98.0% EL-919 for deionized water samples fortified with 0.001-0.1 ppm nifluridide and 0.005-0.1 ppm EL-919. Analysis of water samples (pH 8) from bluegill and rainbow trout toxicity studies with nifluridide resulted in a half-life determination of 10 h at 13°C and 2.5 h at 20°C with nearly quantitative conversion to EL-919 within 96 h.

Chronic toxicity studies were conducted with an alga (Selenastrum capricornutum), a cladoceran (Daphnia magna) and the fathead minnow (Pimephales promelas) to determine their relative sensitivities to tebuthiuron, a soil‐applied herbicide. The alga was the most sensitive of the three species. The no observed effect concentrations for the studies with the fathead minnow (9.3 mg/L) and the cladoceran (21.8 mg/L) were higher than the algistatic concentration (1.5 mg/L) for Selenastrum. These concentrations are 8 to 121 times higher than the highest transient concentration of tebuthiuron reported for a catchment pond.

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