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Full-Text Articles in Physical Sciences and Mathematics
Identification And Quantitation Of Volatile Amines In Chesapeake Bay Sediments, Neeraja Y. Krishna
Identification And Quantitation Of Volatile Amines In Chesapeake Bay Sediments, Neeraja Y. Krishna
Chemistry & Biochemistry Theses & Dissertations
Sediments from different parts of the Chesapeake Bay were analyzed to determine the presence of volatile amines. A HF-HCl extraction method was used to extract both exchangeable and fixed amines from the sediments and a purge-and-trap technique was used to concentrate the amines. Following derivatization with heptafluorobutyric anhydride (HFBA), the HFBA-amines were analyzed by gas chromatography with electron capture detection and with mass spectrometric detection. One primary amine, i-amylamine with a concentration ranging from 0. 78 nmoles/g dry weight to < 0.05 nmoles/g dry weight was found in a total of twenty seven samples collected on three different dates in 1993. Another primary amine, 2-methylbutylamine with a concentration ranging from 0.18 nmoles/g dry weight to < 0.05 nmoles/g dry weight was found in a total of twenty three samples collected on three different dates in 1993. A secondary amine, diethylamine was detected but could not be quantified in a total of seven samples collected in September 1993. The concentrations of these amines varied with location in the Bay, depth in the sediment, and time of year the sediments were collected. The origin of i-amylamine and 2-methylbutylamine might be from the biological decarboxylation of amino acids leucine and isoleucine, respectively. The origin of diethylamine is unknown.
The Isolation And Identification Of Polyphenolics From Grape Seeds And Their Activity Towards Specific Cell Lines, Joseph A. Reddy
The Isolation And Identification Of Polyphenolics From Grape Seeds And Their Activity Towards Specific Cell Lines, Joseph A. Reddy
Chemistry & Biochemistry Theses & Dissertations
Grape seed extract is being marketed in France for cardiovascular use and skin care. The active constituents of both these drugs are certain polyphenols called procyanidins. A similar seed extract has now been obtained from Virginia Chardonnay grape seeds. Ten of the major components in this extract have been isolated in their pure form by the semi-preparative HPLC separation on a YMC ODS-AQ (Octadecylsilane-AQ) column. The ODS-Aq column has been shown to have a better resolving capacity compared to the Spherisorb ODS (Octadecylsilane) column previously described in the literature. This has been attributed to the ODSAQ support which has both …
A Study Of The Chlorination Products Of Methionine In Model Solutions And In Wastewater, D. Scott Winters
A Study Of The Chlorination Products Of Methionine In Model Solutions And In Wastewater, D. Scott Winters
Chemistry & Biochemistry Theses & Dissertations
Model solutions of the amino acid methionine were chlorinated to seven chlorine-to-nitrogen (Cl2/N) molar ratios. After 30 minutes, the solutions were analyzed by high performance liquid chromatography (HPLC). At a Cl2/N molar ratio of 1, methionine sulfoxide was found to be the main product. At Cl2/N molar ratios ≥ 2, a mixture of methionine sulfoxide, methionine sulfone, an unidentified sulfoxide (product 1), and N-chloro-3-(methylsulfonyl) propionaldimine are formed. These products were identified by comparison to synthesized standards which were characterized by 1H-NMR and 13C-NMR nuclear magnetic resonance spectroscopy, ion trap mass spectroscopy, …
Chlorination Products Of Glycylphenylalanine In Model Solutions And A Wastewater, Daniel J. Keefe
Chlorination Products Of Glycylphenylalanine In Model Solutions And A Wastewater, Daniel J. Keefe
Chemistry & Biochemistry Theses & Dissertations
Model solutions of the dipeptide glycylphenylalanine were chlorinated to five different chlorine-to-amino nitrogen (Cl/N) mole ratios and analyzed after 30 min by high performance liquid chromatography. At mole ratios of ≤ 1, N-chloroglycylphenylalanine (I) appeared to be the only major product. At a mole ratio ≤ 2, N, N-dichloroglycylphenylalanine (II) was the only product. Compound II decomposes in model solutions (t1/2= 6.4 hr) at pH 7.0 to form a compound tentatively identified as an H-chloroaldimine (III). Compound III in turn decomposes (t1/2= 36 hr) in model solutions at pH 7. o to (IV) . From 13 …