Matt J. Hengel

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Acrylamide formed in browning model systems was analyzed using a gas chromatograph with a nitrogen-phosphorus detector. Asparagine alone produced acrylamide via thermal degradation at the level of 0.99 microgram/g of asparagine. When asparagine was heated with triolein-which produced acrolein at the level of 1.82 +/- 0.31 (n = 5) mg/L of headspace by heat(More)
An analytical method for the determination of dimethomorph [(E,Z)-4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)acryloyl]morpholine] residues in dried hops was developed utilizing liquid-liquid partitioning, automated gel permeation chromatography (GPC), Florisil and aminopropyl solid phase extraction (SPE) column cleanups, and gas chromatography (GC) with(More)
Heating amino acids with dietary oils or animal fats at elevated temperatures produced various amounts of acrylamide. The amount of acrylamide formation corresponded to the degree of unsaturation of the oils and animal fats. The decreasing order of acrylamide formation from dietary oils or animal fats with asparagine was sardine oil (642 microg/g(More)
Two multiresidue methods were developed to determine pesticides in air collected in California. Pesticides were trapped using XAD-4 resin and extracted with ethyl acetate. Based on an analytical method from the University of California Davis Trace Analytical Laboratory, pesticides were detected by analyzing the extract by gas chromatography-mass(More)
Recent studies indicate that trichloroethylene (TCE) may be a male reproductive toxicant. It is metabolized by conjugation with glutathione and cytochrome p450-dependent oxidation. Reactive metabolites produced along both pathways are capable of forming protein adducts and are thought to be involved in TCE-induced liver and kidney damage. Similarly, in situ(More)
The fate of residues of seven agrochemicals (chlorfenapyr, quinoxyfen, tebuconazole, fenarimol, pyridaben, and E- and Z-dimethomorph) from the treatment on hops to the brewing of beer was studied. First, a multi-residue analytical method was developed for the determination of pesticide residues in spent hops, trub, wort, and beer. Each matrix was validated(More)
Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], in the formulation of Prowl (a commercial herbicide), was applied to various crops. Analysis of pendimethalin and its metabolite [4(1-ethylpropyl)amino-2-methyl-3,5-dinitrobenzyl alcohol] was accomplished by utilizing liquid-liquid partitioning, gel permeation chromatography (GPC) for(More)
Glyoxal, methylglyoxal, and diacetyl formed from sucrose alone and from a D-glucose/ammonia Maillard model system were analyzed by gas chromatography. They are known as precursors of 4(5)-methylimidazole (MI). Glyoxal and methylglyoxal formed more in acidic conditions than in basic conditions, whereas diacetyl formed the most at the highest basic condition(More)
Toxic α-dicarbonyl compounds, glyoxal, 2-methylglyoxal, and diacetyl, released from the headspace from butter, margarine, safflower oil, beef fat, and cheese heated at 100 and 200 °C were analyzed by gas chromatography as quinoxaline derivatives. Total amounts of α-dicarbonyl compounds ranged from 40.5 ng/g (butter) to 331.2 ng/g (beef fat) at 100 °C and(More)