23 research outputs found

    On-line post-column reactions for the analysis of enzyme inhibitors and antioxidants

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    Thermoresponsive poly(N-vinylcaprolactam) as stationary phase for aqueous and green liquid chromatography

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    Poly(N-vinylcaprolactam) (PVCL) connected to aminopropyl silica is a new stationary phase for temperature responsive liquid chromatography (TR-LC). PVCL shows a transition from hydrophilic to hydrophobic interaction between 30 and 40 degrees C. The synthesis is described in detail. The temperature responsive characteristic of the phase is illustrated with a mixture of steroids using pure water as mobile phase. An increase in retention is observed when raising the temperature. H-u plots at different temperatures were constructed. Below the lower critical solution temperature (LCST), no optimal velocity could be measured because of substantial resistance to mass transfer. Above the LCST, u (opt) was ca. 0.3 mm s(-1) with reduced plate heights from 4 at 45 degrees C to 3 at 65 degrees C. The temperature responsive nature of the polymer is lost in green chromatography with ethanol as modifier in concentrations above 5%

    Identification and characterization of a novel cathinone derivative 1-(2,3dihydro-1H-inden-5-yl)-2-phenyl-2-(pyrrolidin-1-yl)-ethanone seized by customs in Jersey

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    A suspicious white powder labeled “idanyl-biphenyl-amninone,” which was seized by customs officials at the "channel island" of Jersey, UK, was brought to our laboratory for identification and characterization of its structure. The elucidation process required the use of several complementary analytical techniques, including gas chromatography–mass spectrometry, liquid chromatography coupled with high-resolution mass spectrometry, nuclear magnetic resonance spectroscopy, and X-ray crystallography. The unknown compound was ultimately identified as 1-(2,3-dihydro-1H-inden-5-yl)-2-phenyl-2-(pyrrolidin-1-yl)-ethanone, a novel cathinone derivative. To the best of our knowledge, this compound has not been registered in the CAS or IUPAC databases. However, it has recently been marketed on the Internet as “indapyrophenidone,” and we therefore propose this as the common name of the compound. The results of this study may serve forensic and clinical laboratories in the identification of its related compounds with similar backbone structure using the information reported in this article obtained by the application of advanced analytical techniques. It may also lead to timely and effective response on the part of legislators and law enforcement

    Mass spectrometric identification and structural analysis of the third-generation synthetic cannabinoids on the UK market since the 2013 legislative ban

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    To examine the impact of the second legal ban on synthetic cannabinoids (SCs) in the UK in February 2013, we surveyed the UK legal high market just before and after the change in legislation, looking for new SCs. The technique gas chromatography–mass spectrometry (GC–MS) in electron ionization mode, most widely applied for analysis, was found to be insufficient for the identification of several SCs, and therefore liquid chromatography–high-resolution mass spectrometry (LC–HR-MS) was required. LC–HR-MS(/MS) measurements of the protonated molecules and product ions allowed the detection of up to 27 compounds as the third-generation SCs in the samples analysed as part of this study, including two unknown compounds that were tentatively identified as F2201 and dealkyl-SDB-006. Our results showed that banned compounds were removed from the market on the day when the ban was in place, and were replaced by other SCs immediately after the ban. In only one occasion, a banned compound (UR-144) was detected after the date when the new legislation came into place. It is also noteworthy that regardless of the change in legislation, new compounds continued to enter the market. Product ion spectral information on the third-generation SCs at different collision energies given in this paper will be of help for forensic and clinical laboratories and will facilitate the detection and identification of new SCs by laboratories of control. This information is very valuable for law enforcement and policymakers and will be of help in future prevention programs

    The fate of quinolizidine alkaloids during the processing of lupins (Lupinus spp.) for human consumption

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    Lupin, a protein-rich grain legume, and products thereof, are becoming increasingly important in our diets. However, variable and high concentrations of quinolizidine alkaloids (QAs) may hamper this evolution. This study assessed the fate of QAs when processing Lupinus albus seeds and lupin-based foods, to give a first indication of the food industry’s ability to sufficiently reduce the QA concentration. Typical unit processes, including toasting, dehulling, sterilization (sterilized jarred lupins), oven baking (cookies), frying (chips) and boiling in water (pasta), were simulated on lab-scale. A quantitative determination of five QAs and qualitative screening of other relevant QAs, in the derived fractions and lupin-based foods, was performed with a validated UHPLC-MS/MS and -HRMS method, respectively. Results revealed that the reduction in quinolizidine alkaloid content is highly dependent on the applied unit process, that QAs appear to be heat stabile, and that the depletion can be attributed to the leaching in cooking water

    The fate of quinolizidine alkaloids during the processing of lupins (Lupinus spp.) for human consumption

    No full text
    Lupin, a protein-rich grain legume, and products thereof may become increasingly important in our diets. However, variable and high concentrations of quinolizidine alkaloids (QAs), i.e. inherent plant toxins, may hamper this evolution. This study intended to assess the fate of QAs when processing Lupinus albus seeds and lupin-based foods, to give a first indication of the food industry’s ability to sufficiently reduce the QA concentration. Typical unit processes, including toasting and dehulling, and the production of relevant food products, i.e. sterilized jarred lupins, cookies, chips and pasta, were identified and simulated on pilot-scale. A quantitative determination of five QAs and qualitative screening of other relevant QAs, in the derived fractions and lupin-based products, was performed with a validated UHPLC-MS/MS method and -HRMS method, respectively. Quinolizidine alkaloids are concentrated in the kernels, appear to be heat stabile, and the depletion of QAs can be attributed to the leaching in cooking water

    Stable Formation of Gold Nanoparticles onto Redox-Active Solid Biosubstrates Made of Squid Suckerin Proteins

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    The use of biomolecules to synthesize inorganic nanomaterials, including metallic nanoparticles, offers the ability to induce controlled growth under mild environmental conditions. Here, recently discovered silk-like “suckerin” proteins are used to induce the formation of gold nanoparticles (AuNPs). Advantage is taken of the distinctive biological and physico-chemical characteristics of suckerins, namely their facile recombinant expression, their solubility in aqueous solutions, and their modular primary structure with high molar content of redox-active tyrosine (Tyr) residues to induce the formation of AuNPs not only in solution, but also from nanostructured solid substrates fabricated from suckerins.NRF (Natl Research Foundation, S’pore)MOE (Min. of Education, S’pore
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