A5055104378- Analytical Chemistry and Chromatography
- Mass Spectrometry Techniques and Applications
- Pesticide Residue Analysis and Safety
- Carcinogens and Genotoxicity Assessment
- Analytical chemistry methods development
- Pesticide and Herbicide Environmental Studies
- Pesticide Exposure and Toxicity
- Toxic Organic Pollutants Impact
- Advanced Chemical Sensor Technologies
- Water Treatment and Disinfection
- Photochemistry and Electron Transfer Studies
- Water Quality Monitoring and Analysis
- Air Quality and Health Impacts
- Chemical Safety and Risk Management
- Electron Spin Resonance Studies
- Conservation, Biodiversity, and Resource Management
- Marine Toxins and Detection Methods
- Analytical Chemistry and Sensors
- Environmental Chemistry and Analysis
- Chromatography in Natural Products
- Isotope Analysis in Ecology
- Aquatic Ecosystems and Phytoplankton Dynamics
- Metabolomics and Mass Spectrometry Studies
- Biodiesel Production and Applications
- Marine and coastal ecosystems
University of Liberia
2024
University of KwaZulu-Natal
2024
California Department of Public Health
2008-2022
Center for Environmental Health
2016
Ford Motor Company (France)
2010
California Health and Human Services Agency
1987-2007
Department of Health Services
1987-2002
National Institute for Occupational Safety and Health
1999
Monsanto (United States)
1999
Ashland (United States)
1999
Agriculture is expanding rapidly across the tropics. While cultivation can boost socioeconomic conditions and food security, it also threatens native ecosystems. Oil palm (Elaeis guineensis), which grown pantropically, most productive vegetable oil crop worldwide. The impacts of have been studied extensively in Southeast Asia - to a lesser extent Latin America but, comparison, very little known about its Africa: palm's range, where rapidly. In this paper, we introduce large-scale research...
Wildfires have destroyed multiple residential communities in California recent years. After fires 2017 and 2018, high concentrations of benzene other volatile organic compounds (VOCs) were found public drinking water systems fire-affected areas. The sources the contamination appropriate remediation been urgent matters investigation. This study characterizes target nontarget VOCs semivolatile (SVOCs) from a highly contaminated service line after 2018 Camp Fire (Paradise, CA). Ninety-five...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolar photooxidation of pesticides in dilute hydrogen peroxideWilliam M. Draper and Donald G. CrosbyCite this: J. Agric. Food Chem. 1984, 32, 2, 231–237Publication Date (Print):March 1, 1984Publication History Published online1 May 2002Published inissue 1 March 1984https://pubs.acs.org/doi/10.1021/jf00122a014https://doi.org/10.1021/jf00122a014research-articleACS PublicationsRequest reuse permissionsArticle Views233Altmetric-Citations56LEARN ABOUT...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemical generation of superoxide radical anion in waterWilliam M. Draper and Donald G. CrosbyCite this: J. Agric. Food Chem. 1983, 31, 4, 734–737Publication Date (Print):July 1, 1983Publication History Published online1 May 2002Published inissue 1 July 1983https://pubs.acs.org/doi/10.1021/jf00118a014https://doi.org/10.1021/jf00118a014research-articleACS PublicationsRequest reuse permissionsArticle Views973Altmetric-Citations48LEARN ABOUT...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHydrogen peroxide and hydroxyl radical: intermediates in indirect photolysis reactions waterWilliam M. Draper Donald G. CrosbyCite this: J. Agric. Food Chem. 1981, 29, 4, 699–702Publication Date (Print):July 1, 1981Publication History Published online1 May 2002Published inissue 1 July 1981https://doi.org/10.1021/jf00106a003RIGHTS & PERMISSIONSArticle Views555Altmetric-Citations44LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum...
This study examines the effects of electrolytes on microcystin (MC) electrospray ionization (ESI) mass spectrometry and quantitative LC-MS-MS. Sodium replacement ions (SRI) are prominent in MC ESI spectra protic solvents such as HPLC grade methanol. In a methanol−water−0.006% acetic acid (v/v) gradient, envelopes with up to 11 SRI were apparent both +1 +2 charge states structures [M + Nax − (x−1)H]+ (x−2)H]+2. The m/z 135 product ion, [Ø—CH2—CH═O—CH3]+, widely used tandem LC-MS-MS...
The performance of a solid phase extraction (SPE) LC-MS-MS procedure for determining microcystins (MC) in water was investigated. Six MC, MCRR, MCYR, MCLR, MCLA, MCLF and MCLW, were determined using positive ion electrospray (+ESI) with separation on C8 column eluted methanol–water gradient containing 15 mM ammonium formate 0.006% acetic acid. Each as well the internal standard surrogate, detected by two transitions. Isocratic separations examined to increase resolution MCRR all known...
High-performance liquid chromatography (HPLC) methods for the determination of phenyl urea herbicides in water are described. The target compounds include chlortoluron, diuron, fluometuron, isoproturon, linuron, metobromuron, metoxuron, monuron, neburon, and siduron. Water was subjected to solid phase extraction (SPE) using either automated SPE with 47 mm C(18) Empore disks or on-line precolumn concentration. Herbicides were separated on a reversed column an acetonitile-water gradient...
The volatile and polar solvent 1,4-dioxane has recently been reported as a contaminant of ground surface waters, establishing the need to determine this substance in drinking water. This investigation established that can be determined water by various techniques including direct aqueous injection (DAI) gas chromatography (GC) purge trap GC-mass spectrometry (MS). Purge GC-MS is limited 1,4-dioxane's poor efficiency, resulting detection limits up 100 times greater than efficiently purged...
Abstract Potential respiratory and dermal exposure to applicators were estimated in a ground boom spray application of 2,4‐D dicamba. Time‐weighted averages for airborne herbicide residues did not exceed 2.2 ug/cu.m. the cabs vehicles allowing only minor exposure. Dermal was important as relatively large amounts (1.2–18 mg) dicamba (0.32–6.6 rinsed from applicators’ hands. Urine analysis showed that maximum elimination herbicides occurred between 16 40 h after terminating A isomer (20%...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiphenyl ether herbicides and related compounds: structure-activity relationships as bacterial mutagensWilliam M. Draper John E. CasidaCite this: J. Agric. Food Chem. 1983, 31, 6, 1201–1207Publication Date (Print):November 1, 1983Publication History Published online1 May 2002Published inissue 1 November 1983https://doi.org/10.1021/jf00120a015RIGHTS & PERMISSIONSArticle Views118Altmetric-Citations28LEARN ABOUT THESE METRICSArticle Views are the...
This study evaluates a new model for identifying unknown compounds in atmospheric pressure ionization mass spectrometry based on mass-to-structure (MTS) paradigm. In this method, rudimentary ESI spectrum interpretation is required to recognize key spectral features such as MH+, MNa+, and MNH4+, which lead the unknown's monoisotopic mass. The associated directly with known organic using an Access 2003 database containing records of 19 438 substances assembled from common sources Merck Index,...
The transport efficiency of the particle beam liquid chromatography/mass spectrometer interface is influenced by analyte concentration contributing to a widely reported non-linearity. In this work, coeluting, isotope-labeled internal standards were investigated as ‘carriers’ improve and linearity. Three styrene metabolites—mandelic, phenylglyoxylic hippuric acids—and their pentadeutero analogs separated reversed-phase chromatography (LC) with an ammonium acetate-acetonitrile mobile phase....
In the context of South Africa’s water scarcity, desalination has emerged as a possible solution for coastal areas. However, quality intake is often problematic, prompting need pre-treatment. The aim this study was to conduct comparative environmental life cycle assessment (LCA) on 4 seawater filtration systems intended pre-treatment reverse osmosis project. These were implemented in pilot trial and are based modern treatment technologies, namely, granular (pressure driven gravity driven),...
Societal Impact Statement Oil palm is native to the west African forest, where industrial production expanding. We assessed differences in plant biodiversity, vegetation structure and provisioning services across 54 community agriculture oil plots Sinoe County, Liberia. Traditional cultivation systems have lower ecological impacts terms of species richness, composition, canopy height structural complexity compared with production, though yields per hectare are likely be lower. can inspire...
This paper describes the characterization of glucuronide and sulfuric acid conjugates alkyl phosphates by thermospray tandem mass spectrometry (MS/MS). Primary spectra were generated using ammonium acetate buffer filament-on ionization with both positive negative ion detection. In mode molecular weight information was obtained for glucuronic, phosphoric other weak acids. Under these conditions, however, not sulfate adducts or phosphate salts. Negative more versatile, providing all metabolic...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDiphenyl ether herbicides: mutagenic metabolites and photoproducts of nitrofenWilliam M. Draper John E. CasidaCite this: J. Agric. Food Chem. 1983, 31, 2, 227–231Publication Date (Print):March 1, 1983Publication History Published online1 May 2002Published inissue 1 March 1983https://pubs.acs.org/doi/10.1021/jf00116a011https://doi.org/10.1021/jf00116a011research-articleACS PublicationsRequest reuse permissionsArticle...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA multiresidue procedure for the determination and confirmation of acidic herbicide residues in human urineWilliam M. DraperCite this: J. Agric. Food Chem. 1982, 30, 2, 227–231Publication Date (Print):March 1, 1982Publication History Published online1 May 2002Published inissue 1 March 1982https://pubs.acs.org/doi/10.1021/jf00110a004https://doi.org/10.1021/jf00110a004research-articleACS PublicationsRequest reuse permissionsArticle...
Phenyl urea herbicides were determined in water by electrospray quadrupole ion trap liquid chromatography-mass spectrometry (ES-QIT-LC-MS). Over a wide concentration range [M - H](-) and MH(+) ions prominent ES spectra. At high concentrations dimer trimer appeared, sodium, potassium, ammonium adducts also observed. In the case of isopturon, source collision-induced dissociation (CID) fragmentation with low offset voltages increased current associated diminished abundance. mass analyzer CID...
This paper describes atmospheric pressure ionization (API) LC-MS-MS determination of urushiols, 3-n-alkenyl- and -alkyl-substituted catechols responsible for poison oak dermatitis. Urushiol was isolated from Western according to the method Elsohly et al. (1) (J. Nat. Prod. 1982, 45, 532-538)-the purified preparation contained C(17)- C(15)-substituted urushiols with zero, one, two, three double bonds as determined GC-MS analysis trimethylsilyl derivatives. mixtures were separated on a C(18)...