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Immature Culicoides variipennis (Coquillett) were sampled from aquatic habitats throughout Virginia, reared to adults, and examined by isozyme electrophoresis to assess their taxonomic status. Data from 22 counties showed that C. v. variipennis is widespread and common, the predominant taxon throughout Virginia, and genetically similar to C. v. variipennis(More)
A market basket study was conducted to measure residues of the insecticide chlorpyrifos in samples of apples, applesauce, apple juice, fresh orange juice, tomatoes, peanut butter, whole milk, ground beef, and pork sausage collected during a 12-month period from 200 grocery stores across the United States. Approximately 90% of the samples contained no(More)
A method is presented for the simultaneous or individual determination of the dinitroaniline herbicides trifluralin, benefin, ethalfluralin, and isopropalin in soil. The herbicides are extracted with acetonitrile-water (99 + 1), and the extracts are purified with small, disposable Florisil cartridges prior to analysis by gas chromatography using an electron(More)
A confirmatory test for the presence of the growth-promoting hormone, diethylstilbestrol (DES), in beef liver is described, Samples are subjected to a published electron capture gas chromatographic method that involves the formation and measurement of the bis-dichloroacetyl derivative of DES. The presence of the derivative is then confirmed by gas(More)
A residue method is described for determination of the aquatic herbicide fluridone (1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone) and its metabolite (1-methyl-3-(4-hydroxyphenyl)-5-[3-(trifluoromethyl) phenyl]-4(1H)-pyridinone) in fish and crayfish tissues. Both compounds are extracted from tissues with methanol, and the extracts are(More)