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W C Brumley

Publications and source records attributed to W C Brumley.

27 records · Page 2Linked to original sources
PubMedDate not supplied

Reactions of antioxidants in foods.

The chemical transformations of BHT and BHA in the deep-fat frying of potatoes were studied. Approximately 80% of the BHT and its associated decomposition products was lost from the lard after six batches of french fries. This may have been due to steam distillation caused by the water boiled out of the potatoes. In contrast, 80% of the radiocarbon introduced as radiolabelled BHA was retained by the frying medium even after 12 batches of french fries. The concentration of intact BHA decreased to undetectable levels after four batches. Because of the complexity of the products formed in the heated fats, studies were undertaken on the thermolysis of a hydroperoxy derivative of BHT, 2,6-di-tert-butyl-4-hydroperoxy-4-methylcyclohexa-2,3-dienone++ + (HBHT). The product mixture, which was identified by mass spectrometry and gas chromatography-mass spectrometry, included BHT, 2,6-di-tert-butyl-4-hydroxy-4-methylcyclohexa-2,5-dienone and 3,5-di-tert-butyl-4-hydroxybenzaldehyde. Elemental compositions of other unidentified products were determined by high-resolution mass spectrometry.

Butylated Hydroxyanisole↗
PubMedDate not supplied

Environmental screening of acidic compounds based on capillary zone electrophoresis/laser-induced fluorescence detection with identification by gas chromatography/mass spectrometry and gas chromatography/high-resolution mass spectrometry.

This paper describes the application of capillary zone electrophoresis/laser-induced fluorescence detection (CZE/LIF) to the discovery of acidic compounds in environmental matrixes or the screening of extracts for acidic components. Published studies indicate that coal-derived materials contain a significant fraction of acidic compounds relative to materials derived from petroleum and shales. Such compounds may be useful as marker compounds for site assessment and source apportionment issues, and their identification may be important in toxicological and other health issues. We used deep-UV light from the frequency-doubled Ar ion laser at 244 and 257 nm to study extracts of samples. The CZE/LIF technique possesses good sensitivity and therefore overcomes one of the limitations of CZE with UV detection. The present work depends on high pressure/temperature solvent extraction of polynuclear aromatic hydrocarbon (PNA)-contaminated soil, followed by separation using CZE. The anionic analytes were separated by using borate or phosphate buffer (pH 9.2-12.3) after a chemical class separation. Samples were also characterized by gas chromatography/mass spectrometry (GC/MS) using full scans at low resolution, and elemental compositions were determined unequivocally by GC/high-resolution MS (GC/HRMS) using mass peak profiling (MPP). The similarity of low-resolution electron ionization mass spectra for a standard, 1-hydroxypyrene, and for a series of compounds in a contaminated-soil extract suggested that several types of phenolic and hydroxy-PNAs were present, including hydroxylated derivatives of fluorenes, fluoranthenes, and pyrenes. GC/HRMS using MPP confirmed the elemental compositions of the hydroxyfluorenes and hydroxypyrenes (and presumably hydroxyfluoranthenes) as [C13H10O] and [C16H10O], respectively. A new version of the MPP software was written for the Finnigan-MAT 900S-Trap and was similar to that developed previously for the VG 250SE. Inclusion of a calibration ion in addition to a lock mass ion in the multiple-ion detection descriptor provided errors of <1 ppm for the 3 partial profiles of the analytes. A mass resolution of 31,000 was used to resolve the analyte signals from interferences evident in the full M+1 and M+2 profiles in the case of the hydroxyfluorenes. Derivatization was also performed to form the tert-butyldimethylsilyl derivatives of phenolic hydroxy groups as a further confirmation of structure.

Acids↗
PubMedDate not supplied

Negative ion chemical ionization mass spectrometric method for confirmation of identity of aflatoxin B1: collaborative study.

An interlaboratory study of a negative ion chemical ionization mass spectrometric (MS) confirmation procedure for aflatoxin B1 was conducted in laboratories in the United States, England, and West Germany. Twelve partially purified, dry film extracts from naturally and artificially contaminated roasted peanuts, cottonseed, and ginger root containing varying quantities of aflatoxin B1 were distributed to the participating laboratories. The extracts required additional cleanup before MS analysis, using either an acidic alumina column and preparative thin layer chromatography (TLC) or a 2-dimensional TLC procedure. Recovery of purified aflatoxin B1 was influenced by the degree of recovery of sample from acid alumina and/or the TLC plate and incomplete elution of aflatoxin B1 from silica gel. Factors affecting MS confirmation included the purity and recovery of aflatoxin and MS instrument sensitivity. Aflatoxin B1 identity was confirmed in 19.5, 90.9, and 100% of samples containing less than 5, 5-10, and greater than 10 ng aflatoxin B1/g product, respectively, by solid probe introduction using full mass scans. The MS method has been adopted official first action.

Aflatoxin B1↗
PubMedDate not supplied

Mass spectrometry and identification of sterols in vegetable oils as butyryl esters and relative quantitation by gas chromatography with flame ionization detection.

Electron ionization mass spectrometry (MS) of sterol butyrates is described. Fragmentation of common sterol butyrates is related to structure and is discussed in relation to the fragmentation of free sterols and of commonly used sterol derivatives. Derivatized samples of vegetable oils are introduced using a 10 m capillary gas chromatographic (GC) column for complete separation of the sterol butyrates. Quantitation of sterol butyrates in vegetable oils by packed column GC/flame ionization detection is based on percent relative area of peaks identified by MS. Results of analyses of sunflower, castor, rapeseed, and virgin olive oils, and other oils are presented. These techniques have been applied to the rapid screening of marketed olive oils for possible adulteration.

Butyrates↗
PubMedDate not supplied

Rapid quantitation and confirmation of aflatoxins in corn and peanut butter, using a disposable silica gel column, thin layer chromatography, and gas chromatography/mass spectrometry.

A simple, rapid, and solvent-efficient method for determining aflatoxins in corn and peanut butter is described. Aflatoxins B1, B2, G1, and G2 were extracted from 50 g sample with 200 mL methanol-water (85 + 15). A portion of the extract was diluted with 10% NaCl solution to a final concentration of 50% methanol, and then defatted with hexane. The aflatoxins were partitioned into chloroform. The chloroform solution was evaporated, and the residue was placed on a 0.5 g disposable silica gel column. The column was washed with 3 mL each of hexane, ethyl ether, and methylene chloride. Aflatoxins were eluted with 6 mL chloroform-acetone (9 + 1). The solvent was removed by evaporation on a steam bath, and the aflatoxins were determined using thin layer chromatography (TLC) with silica gel plates and a chloroform-acetone (9 + 1) developing solvent. Overall average recovery of aflatoxin B1 from corn was 82%, and the limit of determination was 2 ng/g. For mass spectrometric (MS) confirmation, aflatoxin B1 in the extract from 3 g sample (20 ng/g) was purified by TLC and applied by direct on-column injection at 40 degrees C into a 6 m fused silica capillary gas chromatographic column. The column was connected directly to the ion source. After injection, the temperature was rapidly raised to 250 degrees C, and the purified extract was analyzed by negative ion chemical ionization MS.

Aflatoxin B1↗
PubMedDate not supplied

Modular methodology for determination of polychlorinated biphenyls in soil as Aroclors and individual congeners.

A comprehensive screening and confirmatory method was developed for monitoring polychlorinated biphenyls (PCBs), both as Aroclors and as individual congeners. This approach incorporates extraction, extract cleanup, and analysis modules designed to match cost, time, and data quality requirements. Soxhlet, sonication, supercritical fluid, and accelerated solvent extractions were evaluated. Carbon chromatographic cleanup procedures were used for separation of congeners on the basis of ortho substitutions, which permitted calculation of toxicity equivalents. Individual congener determinations, congener total histograms, and peak comparison techniques for Aroclor identification were elaborated by using high and low resolution mass spectrometric data. A screening procedure based on immunoassay using the Ohmicron PCB RaPID Assay kit gave results comparable to those obtained by gas chromatography with electron capture detection in the range 0.40-230 ppm, when the appropriate Aroclor calibrator was used.

Aroclors↗
PubMedDate not supplied

Applications of capillary electrophoresis/laser-induced fluorescence detection to groundwater migration studies.

Capillary electrophoresis has been applied to the determination of groundwater migration based on laser-induced fluorescence (LIF) detection and traditional spectrofluorimetry. Detection limits of injected dye-fluorescent whitening agent (tinopal) in the low ppt ranges have been accomplished with both a spectrofluorometer and with CE/LIF based on the HeCd laser. The real-world problem was the determination of groundwater migration between adjacent Resource Conservation and Recovery Act (RCRA) and Superfund sites. Fluorescent dyes were injected into wells and were discovered in monitoring wells by extracting pads that adsorbed the dye. The methodology based on CE/LIF exhibits increased specificity over existing methodology due to the separation and unique migration time of the dye. Additional studies were aimed at achieving sub-ppt levels in the water directly using solid-phase extraction (SPE) and field-amplified injection techniques.

Electrophoresis, Capillary↗
PubMedDate not supplied

Capillary electrophoretic behavior of seven sulfonylureas.

The electrophoretic behavior of seven sulfonylureas (bensulfuron methyl, sulfometuron methyl, nicosulfuron [accent], chlorimuron ethyl, thifensulfuron methyl [harmony], metsulfuron methyl, and chlorsulfuron) was studied under capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) conditions. Mixtures of these compounds were separated with very high efficiencies (2 x 10(5) theoretical plates) in a running buffer consisting of 3 parts acetate buffer (25 mM, pH 5.0) and 1 part acetonitrile. In this buffer system, acetonitrile was shown to be superior to methanol, acetone, and ethanol as a nonpolar additive, but any of these solvents can be used to reduce electroosmotic flow (EOF) and to obtain adequate separation. On-column detection limits at 214 nM were of the order of 80-100 fM. Micellar agents such as sodium dodecyl sulfate (SDS) and sodium cholate (but not monosialoganglioside-Gm1 or starburst dendrimer, generation 2.5) improved separation in phosphate and borate buffers. Implications of these results for the development of methods to detect these compounds on matrices of environmental origin are discussed. In particular, the instability of these compounds in methanol is noted and degradation products are detected using free zone CE. The methanolysis products of sulfometuron are tentatively identified by tandem MS (negative ion conditions) as 2-amino-4,6-dimethylpyrimidine and 2-carboxymethylbenz(N-carboxymethyl)sulfonamide.

Chromatography↗