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Biomedical subjects

W C Brumley

Publications and source records attributed to W C Brumley.

At least 19 recordsLinked to original sources
PubMed2004

Determination of a bound musk xylene metabolite in carp hemoglobin as a biomarker of exposure by gas chromatography-mass spectrometry using selected ion monitoring.

Musk xylene (MX) is widely used as a fragrance ingredient in commercial toiletries. Identification and quantitation of a bound 4-amino-MX (AMX) metabolite was carried out by gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). Detection of AMX occurred after the cysteine adducts in carp hemoglobin (Hb), derived from the nitroso metabolite, were released by alkaline hydrolysis. The released AMX metabolite was extracted into n-hexane. The extract was preconcentrated by evaporation and analyzed by GC-SIM-MS. The concentration of AMX metabolite was found to range from 6.0 to 30.6 ng/g in the carp Hb, collected from the Las Vegas Wash and Lake Mead, NV areas. The presence of an AMX metabolite in the carp Hb was confirmed when similar mass spectral features and the same retention time of the AMX metabolite were obtained for both standard AMX and carp Hb extract solutions. In the nonhydrolyzed and reagent blank extracts, the AMX metabolite was not detected.

Animals↗
PubMed1999

Capillary electrophoresis and capillary electrochromatography of organic pollutants.

Capillary electrophoresis (CE) has a unique capability for separation of analytes of environmental concern, particularly those that are more polar and ionic, based on the complementary separation principle of electrophoresis. In the past few years, CE has been selectively used to analyze various classes of compounds having current or potential environmental relevance. This review outlines the current status of CE for the determination of environmental pollutants, based predominantly on research results published from the beginning of 1997 to early 1999. Covered are environmental pollutants of all types except pesticides and inorganics. Certain naturally produced toxins are also covered because of their significant impacts upon human health and the environment. CE methods, as with all methods, must be judged on their ability to provide approaches that are reliable, sensitive, selective, and rapid, while meeting "green chemistry" initiatives for pollution prevention. We also compare CE methods to benchmark environmental techniques involving gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and high performance liquid chromatography (HPLC).

Animals↗
PubMed1998

Development of separation systems for polynuclear aromatic hydrocarbon environmental contaminants using micellar electrokinetic chromatography with molecular micelles and free zone electrophoresis.

Of four systems available from the literature, based on cyclodextrins, dioctylsulfosuccinate, bile salts, and molecular micelles consisting of oligomers of undecylenic acid, the most successful separation system in our hands is based on the molecular micelles, oligomers of sodium undecylenic acid (OSUA). We have employed organic additives of acetonitrile, acetone, and tetrahydrofuran in achieving separations of polyaromatic hydrocarbons (PNAs) using molecular micelles. Generally, successful separations are achieved with 20-40% composition as the organic additive in an 8 mM borate buffer. We separated 16 PNAs with 20% tetrahydrofuran in a system of 8 mM borate and 0.125 g/10 mL (ca. 6.25 mM) of OSUA. Typical extracts of environmental samples contain additional analytes besides the typical 16 target compounds. Among these are the nitrogen-containing aromatics that can act as cations under conditions of low pH and additional compounds that can act as anions under basic conditions in free-zone electrophoresis. These additional classes of analytes are separated by capillary zone electrophoresis/laser-induced fluorescence detection using a frequency-doubled laser operated at 257 nm.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed1998

Capillary electrophoresis/laser-induced fluorescence detection of fluorescein as a groundwater migration tracer.

Capillary electrophoresis (CE) has been applied to the determination of the groundwater migration tracer dye fluorescein based on laser-induced fluorescence (LIF) detection and compared to determinations obtained with traditional spectrofluorimetry. Detection limits of injected dye in the low parts per trillion (ppt) ranges have been accomplished with both CE/LIF based on the Ar ion laser and with a spectrofluorimeter. This approach was used for a real-world problem in determining groundwater migration between adjacent Resource Conservation and Recovery Act (RCRA) and Superfund sites by the Environmental Sciences Division in response to regional needs and as application of new analytical tools under development. Fluorescent dye was injected into source wells and then was determined in monitoring wells by extracting pads that adsorbed the dye or by directly determining the dye in the water using solid-phase extraction (SPE), a preconcentration technique. The approaches based on CE/LIF exhibits increased specificity over existing approaches due to the separation and unique migration time of the dye. Additional studies were aimed at achieving sub-ppt levels in the water using solid-phase extraction and field-amplified injection techniques.

Electrophoresis, Capillary↗
PubMed1997

A kinetic study of the methanolysis of the sulfonylureas bensulfuron methyl and sulfometuron methyl using capillary electrophoresis.

The instability of sulfonylureas in solution in methanol has led us to a kinetic study of methanolysis of two sulfonylureas using capillary electrophoresis. In a preliminary experiment, solutions of the seven compounds, bensulfuron methyl, sulfometuron methyl, nicosulfuron, chlorimuron ethyl, thifensulfuron methyl, metsulfuron methyl, and chlorsulfuron were prepared in methanol and in acetonitrile. After six weeks at room temperature the compounds dissolved in acetonitrile were quite stable as shown by electropherograms obtained with free zone capillary electrophoresis (CE). All seven of the compounds dissolved in methanol had undergone extensive degradation and in some cases the sulfonylurea could not be detected. Bensulfuron methyl and sulfometuron methyl were selected for further detailed study. Solutions of these two compounds in methanol were heated at 5, 40, 57, and 65 degrees C. No decomposition of either compound was observed in similar solutions of acetonitrile incubated at 57 degrees C. The rates of decomposition in methanolic solutions were estimated from the decrease in instrumental response representing the peaks of the two sulfonylureas. The methanolysis of both compounds proceeded with pseudo first-order kinetics as evidenced by the fact that semilogarithmic plots of the concentration of the substrate as a function of time were linear (correlation coefficients of 0.99). Rate constants and half-lives for the reactions at 40, 50, 57, and 65 degrees C were determined. These varied by factors of 18 to 22 depending upon the reaction temperature. The energies of activation for these reactions were estimated from the appropriate Arrhenius plots and found to be 26 kcal per mole for bensulfuron methyl and 24.5 kcal per mole for sulfometuron methyl. The kinetics of appearance of the products of methanolysis were directly related to and accurately predicted by the pseudo first-order rate constants observed for disappearance of the sulfonylureas. Kinetic study of the reaction mixture by negative and positive-ion mass spectrometry indicated that the products of methanolysis of sulfometuron methyl were 2-carboxymethyl (N-carboxymethyl)benzsulfonamide and 2-amino-4,6-di-methyl pyrimidine and suggested a general mechanism for methanolysis of each of the seven compounds studied.

Electrophoresis, Capillary↗
PubMed1994

Comparison of micellar electrokinetic chromatography (MEKC) with capillary gas chromatography in the separation of phenols, anilines and polynuclear aromatics potential field-screening applications of MEKC.

Capillary electrophoresis (CE) is known to be complementary to liquid chromatography, but comparison of CE with capillary gas chromatography (GC) for applicable analytes has not been extensive. Capillary GC has been the preeminent separation technique for environmental analysis, but CE has yet to be applied systematically to the determination of environmental analytes. We present data on separations of three classes of semivolatile analytes of interest to environmental analysis: phenols, anilines and polynuclear aromatic hydrocarbons (PNAs). Standard GC conditions were used to illustrate typical separations observed on 30-m and 40-m columns. Rapid analyses were addressed using a high-temperature 15-m column of thinner film. CE separations employed borate buffer with sodium cholate as the micellar agent in micellar electrokinetic chromatography (MEKC). The effects of organic additives were studied using methanol, acetone and tetrahydrofuran. gamma-Cyclodextrin was also used in MEKC to enhance the separation of polynuclear aromatic hydrocarbons and to examine its effects on separations of phenols and anilines. Short capillaries effected very rapid (< 3 min) compound-class characterization, an approach which has potential use in site characterization/remediation (field-screening) studies.

Aniline Compounds↗
PubMed1989

Electron impact mass spectrometry of BHT and its alteration products.

The electron impact (EI) mass spectra of 2,6-di-tert-butyl-4-methylphenol (BHT) and certain of its alteration products are described in detail. Accurate mass measurements confirm the elemental compositions of important fragment ions in the EI spectra. Collisionally activated mass spectra are also used to study fragmentation and suggest common ion structures. The reference spectra provide the basis for identifying various alteration products of BHT by capillary gas chromatography/mass spectrometry (GC/MS) without the necessity of isolating individual components. Application of GC/MS is made to three studies: (i) pyrolysis of hydroperoxy-BHT as a potential pathway to alteration products in food; (ii) GC/MS pyrolysis of hydroperoxy-BHT as a model study; and (iii) alteration of BHT in ethanol/water as a food-simulating solvent.

Butylated Hydroxytoluene↗
PubMed1989

Collisional activation mass spectra of M-. ions of azo dyes containing 2-naphthol.

Collisionally activated decomposition mass spectra of M-. ions of azo dyes are presented. The compounds are of general structure Ar(1)--N = N--Ar(2), where Ar(1) is substituted phenyl and Ar(2) is 2-naphthol. Characteristic fragment ions observed include m/z 157, which corresponds to the 2-naphthol substituent with cleavage of the--N = N--bond represented as [Ar(2)--N]-.. Ion of general structure [Ar(1)--NH]- are also observed. Parent ion scans of m/z 157 provide a potential screening technique for 2-naphthol-containing axo dyes. Specific results are reported for the chloroform extract of FD&C Red #8, and capillary gas chromatographic introduction is compared with direct exposure probe introduction for the identification of dyes.

Azo Compounds↗
PubMed1983

Absorption and distribution patterns of aflatoxicol and aflatoxins B1 and M1 in blood and milk of cows given aflatoxin B1.

Two 600-kg lactating cows were each given a single oral dose (0.5 mg/kg of body weight) of aflatoxin B1 (B1). Samples were obtained at postdosing hours 0, 1, 2, 3, 4, 6, 8, 10, and 12 and thereafter every 12 hours for 10 days. Aflatoxicol (Ro), B1, and aflatoxin M1 (M1) were found in the milk, plasma, and RBC of both cows at postdosing hour 1. Maximum concentrations of the toxins were observed at 12 and 60 hours. The ratio of the concentrations for Ro, B1, and M1 was approximately 1:10:100. Both cows had clinical signs of distress at 24 hours; 1 cow died at 60 hours and the other cow recovered within 4 days. In the samples of liver, kidney, urine, bile, and rumen contents of the cow that died, the B1 concentrations were 5.1, 3.3, 4.1, 1.6, and 320 ng/g, respectively, and the M1 concentrations were 4.3, 20, 37, 16, and 8.6 ng/g. The Ro concentrations in the kidney were approximately equal to that of B1; however, liver, urine, bile, and rumen contents concentrations were 0.88, 0.10, 0.36, and 4.9 ng/g, respectively.

Aflatoxin B1↗
PubMed1982

Aflatoxicol and aflatoxins B1 and M1 in the tissues of pigs receiving aflatoxin.

Aflatoxicol (AFL) and aflatoxins B1 and M1 were found in tissues (kidney, liver, and muscle) of feeder pigs given an estimated LD50 oral dose of B1 (1.0 mg/kg body weight) provided as a rice culture of Aspergillus flavus and of market-weight pigs fed a naturally contaminated feed, containing aflatoxin B1 at a level of 400 ng/g from corn, for 14 days. The residues in all tissues decreased with time after treatment in both groups, with no detectable residues (approximate detection limits, ng/g, B1 0.03, M1 0.05, AFL 0.01) in pig tissues from the feeding experiment 24 h after withdrawal of aflatoxin-contaminated feed. B1 and M1, when found in the feeding experiment, were at about the same levels in all tissues except the kidney, in which M1 was the dominant aflatoxin. The level of AFL, when detected, was about 10% of the B1 level.

Aflatoxin B1↗
PubMed1980

Field desorption mass spectrometry of cyanogenic glycosides.

The field desorption mass spectra of several underivatized cyanogenic glycosides exhibit molecular ions or ions derived from the parent compound by protonation and alkali metal cationization. Abundant fragment ions are present and can be readily related to structure. Significant deviations from established fragmentation pathways are observed due to the nature of the aglycone. The ability to successfully determine the presence of cyanogenic glycosides by field desorption is demonstrated in crude extracts isolated from Vicia sativa, a food-contaminating plant material.

Crystallization↗