Cloransulam-methyl aerobic soil metabolism was investigated to ascertain rates and products of environmental dissipation. Cecil loamy sand and Hanford loam fortified with 66 ng of [ 14 C]cloransulam-methyl g -1 of soil were incubated in the dark at 25 °C and 100 kPa of moisture potential under positive O 2 pressure for up to 357 days. Cloransulam-methyl exhibited a biphasic pattern of degradation. Aerobic soil half-lives were 9 and 13 days, respectively, on Cecil and Hanford soils for data fit to a two-compartment model and 16 and 21 days, respectively, for data fit to a first-order initial rate model. Degradation rates decreased ≈10-fold when soils were incubated at 5 °C or when sterilized by γ-irradiation. Evolved 14 CO 2 accounted for up to 10% of applied 14 C. Metabolites (cloransulam, 5-hydroxycloransulam-methyl, and 5-hydroxycloransulam) occurred in acetone/acetic acid extracts at maximum concentrations of 25, 9, and 8 ng g -1 , respectively, and were significantly less phytotoxic than the parent molecule. Bound residues accumulated up to 76% of applied 14 C. Degradation rate and sorptivity were further investigated on 16 soils fortified with 189 ng g -1 of [ 14 C]cloransulam-methyl and incubated for up to 55 days. Apparent first-order half-lives ranged from 13 to 28 days (mean ( SE ) 18 ( 4 days). Apparent K d values, produced using a two-step extraction, ranged from 0.19 to 4.89 L kg -1 for cloransulam-methyl. Cloransulam-methyl metabolites, when present, tended to exhibit lower K d values than the parent molecule. Apparent K d increased with time.
The ansacarbamitocins are a new family of maytansinoids that are unusually substituted with a glucose subunit and two carbamate functional groups and exhibit modest activity against some agricultural fungal disease organisms. Ansacarbamitocins A-F ( 1- 6) all consist of the same macrocyclic core as the ansamitocins, with variation occurring on the glucose unit, while ansacarbamitocins A1 and B1 ( 7, 8) additionally lack the epoxide group on C-4 and C-5.
Spinosad is an insect control agent that is derived from a naturally occurring soil bacterium and is effective on several classes of insects, especially Lepidoptera larvae. Spinosad is registered in many countries for use on a variety of crops, including cotton, corn, soybeans, fruits, and vegetables. Residue methods utilizing high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection have been described for determining spinosad and its metabolites in environmental and food matrices. These residue methods typically involve an extraction with organic solvents, followed by purification using liquid-liquid partitioning and/or solid phase extraction prior to measurement by HPLC-UV. The residue methods determine the active ingredients (spinosyns A and D) and up to three minor metabolites (spinosyn B, spinosyn K, and N-demethylspinosyn D). The methods have validated limits of quantitation ranging from 0.010 to 0.040 microgram/g. This paper briefly reviews the residue methodology for spinosad and metabolites in food and environmental matrices and provides a summary of method validation results for 61 different sample types, including newly published results for 37 additional crop matrices and processed commodities.
Cloransulam-methyl,
N-(2-carbomethoxy-6-chlorophenyl)-5-ethoxy-7-fluoro[1,2,4]triazolo[1,5-c]pyrimidine-2-sulfonamide, is a new broad-spectrum herbicide for use in
soybeans. The U.S.
Environmental Protection Agency requires that analytical methodology be
developed to enforce
tolerance levels of pesticides in food crops. This paper describes
the method developed to enforce
tolerance levels of cloransulam-methyl in soybeans and soybean forage,
hay, and processed
commodities. The method description includes validation data
supporting a lower limit of
quantitation of 0.01 μg/g (10 ppb) for cloransulam-methyl in each
matrix. Extracts of each matrix
are purified using C18 and neutral alumina solid phase
extraction. Cloransulam-methyl is
derivatized, using (trimethylsilyl)diazomethane, to the
N-methylcloransulam-methyl. Quantitation
and simultaneous confirmation of residues of cloransulam-methyl as
N-methylcloransulam-methyl
employ gas chromatography with mass spectrometric detection using
electron impact ionization
with selected ion monitoring.
Keywords: Cloransulam-methyl; sulfonamide; soybeans;
(trimethylsilyl)diazomethane; GC/MSD
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