- Development of a stable isotope dilution analysis with liquid chromatography-tandem mass spectrometry detection for the quantitative analysis of di- and trihydroxybenzenes in foods and model systems
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A straightforward stable isotope dilution analysis (SIDA) for the quantitative determination of the di-and trihydroxybenzenes catechol (1), pyrogallol (2), 3-methylcatechol (3), 4-methylcatechol (4), and 4-ethylcatechol (5) in foods by means of liquid chromatography-tandem mass spectrometry was developed. With or without sample preparation involving phenylboronyl solid phase extraction, the method allowed the quantification of the target compounds in complex matrices such as coffee beverages with quantification limits of 9 nmol/L for 4-ethylcatechol, 24 nmol/L for catechol, 3-methyl-, and 4-methylcatechol, and 31 nmol/L for pyrogallol. Recovery rates for the analytes ranged from 97 to 103%. Application of the developed SIDA to various commercial food samples showed that quantitative analysis of the target compounds is possible within 30 min and gave first quantitative data on the amounts of di- and trihydroxybenzenes in coffee beverage, coffee powder, coffee surrogate, beer, malt, roasted cocoa powder, bread crust, potato crisps, fruits, and cigarette smoke and human urine. Model precursor studies revealed the carbohydrate/amino acid systems as well as the plant polyphenols catechin and epicatechin as precursors of catechol and 5-O-caffeoylquinic acid, caffeic acid as a precursor of catechol and 4-ethylcatechol, and gallocatechin, epigallocatechin, and gallic acid as precursors of pyrogallol.
- Lang, Roman,Mueller, Christoph,Hofmann, Thomas
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- Stereochemistry of the enzymic lactonisation of cis,cis-muconic and 3-methyl-cis,cis-muconic acid
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Experiments with 4-methyl[3,5,6-2H3]pyrocatechol 7 have shown that the product of its enzymic oxygenation, 3-methyl-cis,cis-muconic acid 8, undergoes enzymic cyclisation by syn addition of carboxy groups to distal double bonds to for
- Chen, Beining,Kirby, Gordon W.,Rao, Ghanakota V.,Cain, Ronald B.
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- Aromatic ring favorable and efficient H-D exchange reaction catalyzed by Pt/C
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An effective and applicable Pt/C-catalyzed deuteration method of aromatic rings using D2O as a deuterium source under hydrogen atmosphere was developed. Five percent Pt/C would lead to quite effective H-D exchange results on the aromatic ring systems. The reaction is general for a variety of aromatic compounds including biologically active compounds.
- Sajiki, Hironao,Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Maegawa, Tomohiro,Hirota, Kosaku
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- Fragmentation of Collisionally Activated Hydroxyphenoxide Anions in the Gas Phase
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Low-energy collisionally activated dissociation of O-deprotonated dihydroxybenzenes (catechol, resorcinol, hydroquinone) in the gas phase causes both fragmentation to form (-) ions by loss of the remaining oxygen-bound hydrogen atom and intramolec
- Binkley, Roger W.,Dillow, Glen W.,Flechtner, Thomas W.,Winnik, Witold,Tevesz, Michael J. S.
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- Elucidation of the Coordination Chemistry of the Enzyme-Substrate Complex of Catechol 1,2-Dioxygenase by NMR Spectroscopy
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The coordination chemistry of the active site iron in catechol 1,2-dioxyygenase (CTD) from Pseudomonas putida (ATCC 23974) has been probed with NMR spectroscopy.The high-spin ferric center gives rise to paramagnetically shifted resonances in the range of
- Que, Lawrence,Lauffer, Randall B.,Lynch, John B.,Murch, Bruce P.,Pyrz, Joseph, W.
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- Deuterated dopamine as well as preparation method and application thereof
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The invention discloses deuterated dopamine as well as a preparation method and application thereof. The chemical structural general formula of the deuterated dopamine is shown in the specification, wherein at least one of R1, R2, R3, R4 and R5 is deuteri
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Paragraph 0025; 0033
(2021/03/13)
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- Efficient and selective Pt/C-catalyzed H-D exchange reaction of aromatic rings
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An effective and applicable deuteration method for aromatic rings using Pt/C-D2O-H2 system was established. Especially, phenol was fully deuterated even at room temperature, and other electron-rich aromatic nuclei were efficiently deuterated under mild conditions. The scope and limitations of the presence method and its application to the synthesis of deuterium-labeled biologically active compounds and deuterium-labeled building blocks for practical multi-gram scale syntheses are reported. 2008 The Chemical Society of Japan.
- Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Imamiya, Eikoh,Maegawa, Tomohiro,Sajiki, Hironao
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experimental part
p. 278 - 286
(2009/03/12)
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- A simple procedure for the deuteriation of phenols
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A simple procedure for the deuteriation of a large range of phenols has been developed using Amberlyst 15, a polymer supported acid catalyst. A number of phenols present in olive oil have been successfully deuteriated. The aromatic protons of hydroxytyrosol are 100% exchanged under the conditions used. This method is applicable for the tritiation of phenols.
- Tuck, Kellie L.,Tan, Hai-Wei,Hayball, Peter J.
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p. 817 - 823
(2007/10/03)
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- Electron Spin Resonance Studies of Radicals derived from 1,3,2-Benzodioxaboroles
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The reactions of photochemically generated ethoxyl and t-butoxyl radicals with a number of 1,3,2-benzodioxaboroles and with 2-butyl-4,5-dimethyl-1,3,2-dioxaborole have been studied in solution using e.s.r. spectroscopy.With each borole, alkoxyl addition t
- Baban, Jehan A.,Goodchild, Nicholas J.,Roberts, Brian P.
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p. 157 - 162
(2007/10/02)
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