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Gunatilake S.R.,Mississippi State University | Clark T.L.,Mississippi State University | Rodriguez J.M.,Mississippi State Chemical Laboratory | Mlsna T.E.,Mississippi State University
Analytical Methods | Year: 2014

Comprehensive two-dimensional gas chromatography (GC × GC) hyphenated with rapid quadrupole mass spectrometry was successfully used to develop a novel method for the determination of trace level estrogens in influent and effluent wastewater. Five estrogens used for the study were 17β-estradiol (βE2), 17α-estradiol (αE2), estrone (E1), 17α- ethynylestradiol (EE2) and estriol (E3). Two orthogonal columns and thermal modulation result in enhanced separation, while the rapid scanning quadrupole mass spectrometer gives high resolution peaks. Samples were extracted with Hydrophilic-Lipophilic Balance (HLB) cartridges and derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) prior to analysis. The method uses a single extraction step and ng L-1 method detection limits were achieved using a relatively low sample volume of 500 mL. Elimination of additional cleanup steps make the method time effective. Furthermore, the method has less initial cost as the instrument is far less expensive than a tandem mass spectrometer. A parallel conventional gas chromatographic-mass spectrometric (GC/MS) study was carried out to compare the results. Detection limits were 2 to 4 times improved with the GC × GC over the GC/MS. © 2014 The Royal Society of Chemistry.

Bowling J.J.,University of Mississippi | Anderson J.B.,University of Mississippi | Armbrust K.L.,Mississippi State Chemical Laboratory | Hamann M.T.,University of Mississippi
Fuel | Year: 2014

Oil production from single cells has been in development since the 1980s primarily for the pharmaceutical and neutraceutical industries, but the technology for using microorganisms to convert plant cellular material directly into oil is still undeveloped. The unusual amount of oil extracted from the imported fire ant (Solenopsis sp.) may be an indication of the presence of oleaginous microorganisms or enzymes supporting the digestion of raw sugars. Yield of the ant oil is 16% dry weight and contains most of the fatty acids also found in other biomass resources. Heat of combustion of the ant oil was 133,000 BTU/gal, an amount within the range of reported values for vegetable oil and biodiesel. This investigation also explores the potential source of the oil through stable isotope labeling and offers a unique perspective of a potentially new source of microorganisms or enzymes useful for reducing the cost of producing an alternative fuel. © 2013 Elsevier Ltd. All rights reserved.

Taylor C.M.,Shimadzu | Raines J.M.,Mississippi State Chemical Laboratory | Rodriguez J.M.,Mississippi State Chemical Laboratory | Rodriguez J.M.,Mississippi State University
Food Analytical Methods | Year: 2013

The aim of this project is to determine polycyclic aromatic hydrocarbons (PAHs) in several seafood matrices, i.e., fish, and mussel, by the use of comprehensive two-dimensional gas chromatography-quadrupole mass spectrometry (GCXGC-MS). The procedure involves a simple extraction of PAHs, a filtration and concentration step followed by GCXGC-MS analysis. PAHs were determined in fish tissue samples by GCXGC-MS and by a standard high-pressure liquid chromatography fluorescence detector method. A Bland-Altman analysis of the two methods was performed. It indicated equivalence between the two methods. Analysis of mussel tissue (National Institute of Standards and Technology (NIST)-SRM 2974a) was performed. The results were in line with the official results of NIST. © 2012 Springer Science+Business Media New York.

Revellame E.,Mississippi State University | Hernandez R.,Mississippi State University | French W.,Mississippi State University | Holmes W.,Mississippi State Chemical Laboratory | Alley E.,Mississippi State Chemical Laboratory
Journal of Chemical Technology and Biotechnology | Year: 2010

BACKGROUND: The microbial biomass present in activated sludge contains lipidic compounds that can be used as biodiesel feedstock. In this study, the production of biodiesel from activated sludge from Tuscaloosa, AL was optimized based on the yield of fatty acid methyl esters (FAMEs). In situ transesterification was used with sulfuric acid as catalyst. A general factorial design of 4 × 6 × 5 for temperature, methanol to sludge ratio and catalyst concentration, respectively, was considered for optimization. RESULTS: Biodiesel yield can be adequately described by the quadratic response surfacemodel with R 2 of 0.843 and statistically insignificant lack of fit (p = 0.152).Numerical optimization showed that an optimum biodiesel yield of 4.88% can be obtained at 55 °C, 25 methanol to sludge ratio and4%volume sulfuric acid. The optimum experimental biodiesel yieldwas indeed obtained at that condition but with a value of 4.79 ± 0.02%. The highest error was 2.30% which indicates good agreement between the model and the experimental data. CONCLUSIONS: Acid-catalyzed polymerization of unsaturated fatty acids or their esters at temperature above 60° Csignificantly decreased biodiesel yield. The fatty acid profile of the biodiesel produced indicates that activated sludge may be used as biodiesel feedstock. © 2010 Society of Chemical Industry.

Womack E.D.,Molecular Biology | Brown A.E.,Molecular Biology | Brown A.E.,Mississippi State Chemical Laboratory | Sparks D.L.,Molecular Biology | Sparks D.L.,Mississippi State Chemical Laboratory
Journal of the Science of Food and Agriculture | Year: 2014

Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic compounds produced predominantly as secondary metabolites by certain species of fungi belonging to the Aspergillus genus. Owing to the significant health risks and economic impacts associated with the presence of aflatoxins in agricultural commodities, a considerable amount of research has been directed at finding methods to prevent toxicity. This review compiles the recent literature of methods for the detoxification and management of aflatoxin in post-harvest agricultural crops using non-biological remediation. © 2013 Society of Chemical Industry.

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