A rapid quantitative bioassay for the determination of biologically available bromacil in soils

Abstract

A simple rapid bioassay is described for the determination of biologically available bromacil residues in soils. A clear aqueous extract was made from a soil fortified with a known amount of the herbicide, and similar extracts were made from samples of soil taken from plots that had been sprayed with a bromacil formulation at a rate of 4 kg ha−1. Samples of these extracts were added to a suspension of the unicellular green alga Selenastrum capricornutum. The net photosynthetic oxygen production by the alga was then measured using an oxygen electrode. The results were expressed as a percentage of the oxygen production by a control suspension. The concentration of biologically available bromacil was determined by reference to a previously established dose‐response curve of the percentage reduction in oxygen production against bromacil concentration. The accuracy of this bioassay was determined by comparing the results with those obtained using capillary gas‐liquid chromatography. The results obtained by the two different methods showed good agreement.

An enzyme immunoassay for the environmental monitoring of the herbicide bromacil

“…Considerable interest has been focused on the environmental monitoring of this compound as well as the study its transport processes in environmental elements (Alva and Singh, 1990; U.S. Environmental Protection Agency, 1990; Worthing and Hance, 1991;Allender, 1991;Jaynes, 1991;Reddy et al, 1992) because of its wide application and recent concerns about health hazards (Garrett et al, 1986; Call et al, 1987; Parent et al, 1990). Most chromatographic residue analyses for bromacil at trace levels require laborious cleanup procedures or expensive instrumentation (Gar-diner, 1975; Bennett and de Beer, 1984;Putzien, 1987;Goewie and Hogendoorn, 1987;Frohlich and Meier, 1989; Lipschitz et al, 1989;Wylie and Oguchi, 1990; Stan and Heil, 1991;Tuinstra et al, 1991;Foster et al, 1991). An immunochemical determination could provide a simpler approach for detection of this pesticide at trace levels (Hammock and Mumma, 1980;Gee et al, 1988; Schlaeppi et al, 1989; Goodrow et al, 1990;Li et al, 1991;Forlani et al, 1992).…”

Synthesis of haptens and conjugates for an enzyme immunoassay for analysis of the herbicide bromacil

“…Some recent procedures are based on still more sophisticated equipment (Wylie and Oguchi, 1990;Stan and Heil, 1991). Bioassays for bromacil appear to lack the necessary selectivity (Benett and de Beer, 1984;Yanase et al, 1990; Zimmermann et al, 1990). Immunoassays have been demonstrated to be simple and costeffective alternatives to instrumental analyses when numerous samples need to be investigated for monitoring environmental pollutants or contaminants in agricultural products (Cheung et al, 1988;Vanderlaan et al, 1988;Hammock et al, 1990; Teshima et al, 1990; Hall, 1990; Newsome and Collins, 1991).…”

Bioassay of Photosynthetic Inhibitors in Water and Aqueous Soil Extracts with Eurasian Watermilfoil (Myriophyllum spicatum)

“…Eurasian watermilfoil grew rapidly in culture with a doubling time of 8 to 10 days and, under controlled conditions, an oxygen evolution rate of 2.6 ± .1 mg 02g~^ fr wt-mur 1 . Oxygen evolution by untreated shoots was linearly correlated (r = 0.999) with time for periods up to 50 min.…”

“…Substituted urea, triazine, and uracil herbicides, which characteristically inhibit photosynthesis (4), block photoinduced electron transport at the primary site of action (7,19). The property of photosynthesis-inhibiting herbicides affecting oxygen evolution during photosynthesis has often been used as a measured response for bioassaying photosynthetic inhibitors in water (18) and soils (1,17). During a study to determine the exposure time required to control Eurasian watermilfoil with simazine, the potential of using milfoil as a bioassay plant became apparent.…”