The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform
N. Lee Wolfe - One of the best experts on this subject based on the ideXlab platform.
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Uptake and phytotransformation of organophosphorus pesticides by axenically cultivated aquatic plants.
Journal of agricultural and food chemistry, 2000Co-Authors: Jianping Gao, A. Wayne Garrison, Christopher Hoehamer, And C. S. Mazur, N. Lee WolfeAbstract:The uptake and phytotransformation of organophosphorus (OP) pesticides (malathion, demeton-S-methyl, and Crufomate) was investigated in vitro using the axenically aquatic cultivated plants parrot feather (Myriophyllum aquaticum), duckweed (Spirodela oligorrhiza L.), and elodea (Elodea canadensis). The decay profile of these OP pesticides from the aqueous medium adhered to first-order kinetics. However, extent of decay and rate constants depended on both the physicochemical properties of the OP compounds and the nature of the plant species. Malathion and demeton-S-methyl exhibited similar transformation patterns in all three plants: 29−48 and 83−95% phytotransformation, respectively, when calculated by mass recovery balance during an 8-day incubation. No significant disappearance and phytotransformation of Crufomate occurred in elodea over 14 days, whereas 17−24% degraded in the other plants over the same incubation period. Using enzyme extracts derived from duckweed, 15−25% of the three pesticides were t...
A W Garrison - One of the best experts on this subject based on the ideXlab platform.
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application of capillary electrophoresis to study the enantioselective transformation of five chiral pesticides in aerobic soil slurries
Journal of Agricultural and Food Chemistry, 2005Co-Authors: J L Jarman, W J Jones, L A Howell, A W GarrisonAbstract:The enantiomers of five chiral pesticides of environmental interest, metalaxyl, imazaquin, fonofos (dyfonate), ruelene (cruformate), and dichlorprop, were separated analytically using capillary electrophoresis (CE) with cyclodextrin chiral selectors. For metalaxyl, imazaquin, and fonofos, aqueous slurries of soil samples from two sites in Georgia and one in Ohio were spiked with the racemate of each pesticide at 50-60 mg/L of aqueous phase of the slurry, and CE analyses were performed at various time intervals to determine enantiomer fractions (EF). Metalaxyl underwent enantioselective transformation; in one soil, the half-life of the target active R-(+)-enantiomer was 17 days while that for the S-(-)-enantiomer was 69 days. Transformation occurred more slowly in the other two soils but was still selective for the R-(+)-enantiomer. Imazaquin and fonofos exhibited nonselective enantiomer loss over their 3 months of incubation time; this could have been due to abiotic or nonselective microbial reactions. Ruelene and dichlorprop were transformed selectively in a variety of soils in a previously reported study (7) that showed the influence of environmental changes on the transformation of chiral pollutants in soils; analytical methods used in that study are reported here to further illustrate the application of CE. CE is shown to be a simple, efficient, and inexpensive way to follow the transformation of chiral pesticides in laboratory microcosms where concentrations can be made high enough (25-50 mg/L initial racemate concentration) for detection of residual parent enantiomers during most of the process.
Jianping Gao - One of the best experts on this subject based on the ideXlab platform.
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Uptake and phytotransformation of organophosphorus pesticides by axenically cultivated aquatic plants.
Journal of agricultural and food chemistry, 2000Co-Authors: Jianping Gao, A. Wayne Garrison, Christopher Hoehamer, And C. S. Mazur, N. Lee WolfeAbstract:The uptake and phytotransformation of organophosphorus (OP) pesticides (malathion, demeton-S-methyl, and Crufomate) was investigated in vitro using the axenically aquatic cultivated plants parrot feather (Myriophyllum aquaticum), duckweed (Spirodela oligorrhiza L.), and elodea (Elodea canadensis). The decay profile of these OP pesticides from the aqueous medium adhered to first-order kinetics. However, extent of decay and rate constants depended on both the physicochemical properties of the OP compounds and the nature of the plant species. Malathion and demeton-S-methyl exhibited similar transformation patterns in all three plants: 29−48 and 83−95% phytotransformation, respectively, when calculated by mass recovery balance during an 8-day incubation. No significant disappearance and phytotransformation of Crufomate occurred in elodea over 14 days, whereas 17−24% degraded in the other plants over the same incubation period. Using enzyme extracts derived from duckweed, 15−25% of the three pesticides were t...
William L Champion - One of the best experts on this subject based on the ideXlab platform.
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High-performance liquid chromatographic separation of the enantiomers of organophosphorus pesticides on polysaccharide chiral stationary phases
Journal of chromatography. A, 2001Co-Authors: J. Jackson Ellington, John J. Evans, Keith B. Prickett, William L ChampionAbstract:Abstract High-performance liquid chromatographic separation of the individual enantiomers of 12 organophosphorus pesticides (OPs) was obtained on polysaccharide enantioselective HPLC columns using alkane–alcohol mobile phase. The OP pesticides were crotoxyphos, dialifor, fonofos, fenamiphos, fensulfothion, isofenphos, malathion, methamidophos, profenofos, Crufomate, prothiophos and trichloronate. The enantiomers of fenamiphos, fensulfothion, profenofos and Crufomate were separated on CHIRALPAK ® AD ® ; the enantiomers of fenamiphos were also separated on CHIRALPAK ® AS ® ; the enantiomers of methamidophos, Crufomate and trichloronate were separated on CHIRALCEL ® OD ® ; the enantiomers of crotoxyphos, dialifor, fonofos, malathion, prothiophos and trichloronate were separated on CHIRALCEL ® OJ ® ; and the enantiomers of isofenphos were separated on CHIRALCEL ® OG ® . Baseline or partial separation of the enantiomers of six of these OP pesticides was obtained on CHIRALCEL ® OJ. In continued method development, the separation of the enantiomers of the 12 OPs was investigated more extensively on CHIRALCEL ® OJ to determine whether the mobile phase composition, flow-rate and column temperature could be optimized to yield at least partial separation of the enantiomers. Chromatographic conditions were found that gave either baseline or near baseline separations of the enantiomers of the 12 OPs on the CHIRALCEL ® OJ column.
J L Jarman - One of the best experts on this subject based on the ideXlab platform.
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application of capillary electrophoresis to study the enantioselective transformation of five chiral pesticides in aerobic soil slurries
Journal of Agricultural and Food Chemistry, 2005Co-Authors: J L Jarman, W J Jones, L A Howell, A W GarrisonAbstract:The enantiomers of five chiral pesticides of environmental interest, metalaxyl, imazaquin, fonofos (dyfonate), ruelene (cruformate), and dichlorprop, were separated analytically using capillary electrophoresis (CE) with cyclodextrin chiral selectors. For metalaxyl, imazaquin, and fonofos, aqueous slurries of soil samples from two sites in Georgia and one in Ohio were spiked with the racemate of each pesticide at 50-60 mg/L of aqueous phase of the slurry, and CE analyses were performed at various time intervals to determine enantiomer fractions (EF). Metalaxyl underwent enantioselective transformation; in one soil, the half-life of the target active R-(+)-enantiomer was 17 days while that for the S-(-)-enantiomer was 69 days. Transformation occurred more slowly in the other two soils but was still selective for the R-(+)-enantiomer. Imazaquin and fonofos exhibited nonselective enantiomer loss over their 3 months of incubation time; this could have been due to abiotic or nonselective microbial reactions. Ruelene and dichlorprop were transformed selectively in a variety of soils in a previously reported study (7) that showed the influence of environmental changes on the transformation of chiral pollutants in soils; analytical methods used in that study are reported here to further illustrate the application of CE. CE is shown to be a simple, efficient, and inexpensive way to follow the transformation of chiral pesticides in laboratory microcosms where concentrations can be made high enough (25-50 mg/L initial racemate concentration) for detection of residual parent enantiomers during most of the process.