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This study reports the convenient, low cost, one-step synthesis of labelled analogues of six volatile phenols, guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, eugenol and vanillin, using microwave-assisted deuterium exchange, for use as internal standards for stable isotope dilution analysis. The current method improves on previous strategies in that it enables incorporation of deuterium atoms on the aromatic ring, thereby ensuring retention of the isotope label during mass spectrometry fragmentation. When used as standards for SIDA, these labelled volatile phenols will improve the accuracy and reproducibility of quantitative food and beverage analysis.
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http://dx.doi.org/10.1016/j.foodchem.2014.04.051 | DOI Listing |
PNAS Nexus
July 2022
Birck Nanotechnology Center, Purdue University, 1205 W State St, West Lafayette, 47907 IN, USA.
Lyophilization is a common unit operation in pharmaceutical manufacturing but is a prolonged vacuum drying process with poor energy utilization. Microwave-assisted vacuum drying has been investigated to accelerate the lyophilization process. However, the literature lacks methodical approaches that consider the lyophilizer, the lyophilizate, the microwave power uniformity, the resulting heat uniformity, and the scalability.
View Article and Find Full Text PDFOrg Lett
May 2019
Laboratoire de Synthèse Organique , Ecole Polytechnique , CNRS UMR 7652, Palaiseau 91128 Cedex , France.
A series of conjugated 4-alkenyl-1,3-dithiol-2-ones have been prepared by microwave-assisted rearrangement of S-(4-acyloxy-2-alkynyl)- O-ethyl xanthates in moderate to good yields. The synthetic approach is based on a combination of [3,3] and [1,5] sigmatropic rearrangements as well as the intermediacy of a reactive betaine that induces the ionic elimination of the acyloxy group. The [1,5] sigmatropic rearrangement was confirmed by a deuterium-labeling experiment.
View Article and Find Full Text PDFCarbohydr Polym
November 2017
Department of Applied Chemistry, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, Johannesburg, South Africa; Centre for Nanomaterials Science Research, University of Johannesburg, South Africa.
In the present project, graft polymerization was employed to synthesis a novel adsorbent using acrylic acid (AA) and xanthan gum (XG) for cationic methylene dye (MB) removal from aqueous solution. The XG was rapidly grafted with acrylic acid (CH=CHCOOH) under microwave heating. Fourier-transform infrared spectroscopy (FTIR), Proton Nuclear magnetic resonance spectroscopy (H NMR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Thermal gravimetric analysis (TGA) techniques were used to verify the adsorbent formed under optimized reaction conditions.
View Article and Find Full Text PDFFood Chem
November 2014
The University of Adelaide, School of Agriculture, Food and Wine, PMB 1, Glen Osmond, SA 5064, Australia. Electronic address:
This study reports the convenient, low cost, one-step synthesis of labelled analogues of six volatile phenols, guaiacol, 4-methylguaiacol, 4-ethylguaiacol, 4-ethylphenol, eugenol and vanillin, using microwave-assisted deuterium exchange, for use as internal standards for stable isotope dilution analysis. The current method improves on previous strategies in that it enables incorporation of deuterium atoms on the aromatic ring, thereby ensuring retention of the isotope label during mass spectrometry fragmentation. When used as standards for SIDA, these labelled volatile phenols will improve the accuracy and reproducibility of quantitative food and beverage analysis.
View Article and Find Full Text PDFJ Am Chem Soc
August 2013
Green Chemistry Centre of Excellence, Department of Chemistry, University of York, York, YO10 5DD, UK.
A systematic investigation of the interaction of microwave irradiation with microcrystalline cellulose has been carried out, covering a broad temperature range (150 → 270 °C). A variety of analytical techniques (e.g.
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