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41.
Iva ikuten Petra tambuk Jasminka Karoglan Konti Edi Maleti Ivana Tomaz Darko Preiner 《Molecules (Basel, Switzerland)》2021,26(23)
(1) Background: Solid phase microextraction (SPME)-Arrow is a new extraction technology recently employed in the analysis of volatiles in food materials. Grape volatile organic compounds (VOC) have a crucial role in the winemaking industry due to their sensory characteristics of wine.; (2) Methods: Box–Behnken experimental design and response surface methodology were used to optimise SPME-Arrow conditions (extraction temperature, incubation time, exposure time, desorption time). Analyzed VOCs were free VOCs directly from grape skins and bound VOCs released from grape skins by acid hydrolysis.; (3) Results: The most significant factors were extraction temperature and exposure time for both free and bound VOCs. For both factors, an increase in their values positively affected the extraction efficiency for almost all classes of VOCs. For free VOCs, the optimum extraction conditions are: extraction temperature 60 °C, incubation time 20 min, exposure time 49 min, and desorption time 7 min, while for the bound VOCs are: extraction temperature 60 °C, incubation time 20 min, exposure time 60 min, desorption time 7 min.; (4) Conclusions: Application of the optimized method provides a powerful tool in the analysis of major classes of volatile organic compounds from grape skins, which can be applied to a large number of samples. 相似文献
42.
Determination of extractable chromium from leather 总被引:1,自引:0,他引:1
Abstract People are exposed to chromium ions from leather materials due to everyday contact with different textile objects. The problem
is that Cr(VI) is extremely toxic and may cause contact allergic dermatitis on the skin and may also be a trigger for many
diseases. Huge amounts of chromium ions are released by waste waters to rivers after chromium-tanning processes in the leather
industry; the presence of chromium is not only a problem for human health, but also for the environment. For this reason it
is extremely important to monitor the presence of chromium as Cr(VI) and as total chromium. This study aims to present an
appropriate analytical method for monitoring Cr(VI) and the total chromium present on leather materials. Applying this method
to chromium-tanned leather samples, it was observed that the amounts of total chromium as well as of Cr(VI) are higher than
prescribed and recommended by different regulations. Chromium(VI) exceeded the limit of 3 mg/kg in the majority of tested
materials, while the total chromium exceeded the limit of 50 mg/kg in all tested samples. For this reason, it is recommended
to avoid direct and prolonged contact of those materials with the skin.
Graphical abstract
相似文献
43.
When tin is to be determined in such a complex matrix like aqua regia extracts of environmental samples by electrothermal atomic absorption spectrometry (ETAAS), spectral interferences occur when deuterium-lamp (D2) background correction is used, even using high pyrolysis temperature of 1400 °C achieved with palladium with citric acid chemical modifier. We have found that the further addition of NH4F to palladium with citric acid chemical modifier is essential for overcoming the above-mentioned problems for which aluminium oxide is most probably responsible. It is supposed, that NH4F enables volatilization of the alumina matrix formed by hydrolysis from the chloride salt and interfering in a gas phase via the formation of AlF3 which could be, in contrast to aluminium oxide, removed from the graphite furnace during the pyrolysis stage. Using the proposed chemical modifier, the direct and accurate determination of Sn in aqua regia extracts from rocks, soils and sediments is possible even when using matrix free standard solutions. This presumption was confirmed by the analysis of certified reference samples and by the comparison with inductively coupled plasma time of flight mass spectrometry (ICP-TOFMS) method. Characteristic mass and LOD value for the original sample (10-μL aliquots of sample) was 17 pg and 0.055 μg g−1, respectively. 相似文献
44.
Iva Movre Šapić Vesna Volovšek Krešimir Furić Lahorija Bistričić Vladimir Dananić 《Macromolecular Symposia》2011,305(1):122-125
In this work we investigated the solidification of aminopropylsilanetriol dissolved in water (∼25%) under different conditions by Raman spectroscopy. The solidification was carried out at three different temperatures 8 °C, 23 °C and 60 °C. The influence of electromagnetic radiation on the polymerization process was also studied. Samples were held to solidify in dark and at UV (254 nm and 356nm) spectral range. In order to investigate the influence of the substrate on the resulting polymer structure, teflon, PVC, glass, brass and silica were used. Best ordered polymerized structure was achieved for samples deposited on plastics and solidified in dark, at room temperature. 相似文献
45.
Rowena Held Iva Stavrov Brian VanKoten 《Differential Geometry and its Applications》2009,27(4):464-481
We use reduced homogeneous coordinates to construct and study the (semi-)Riemannian geometry of the octonionic (or Cayley) projective plane , the octonionic projective plane of indefinite signature , the para-octonionic (or split octonionic) projective plane and the hyperbolic dual of the octonionic projective plane . We also show that our manifolds are isometric to the (para-)octonionic projective planes defined classically by quotients of Lie groups. 相似文献
46.
Katherine A. Gibney Iva Sovadinova Analette I. Lopez Michael Urban Zachary Ridgway Gregory A. Caputo Kenichi Kuroda 《Macromolecular bioscience》2012,12(9):1279-1289
We report the structure–activity relationship in the antimicrobial activity of linear and branched poly(ethylene imine)s (L‐ and B‐PEIs) with a range of molecular weights (MWs) (500–12 000). Both L‐ and B‐PEIs displayed enhanced activity against Staphylococcus aureus over Escherichia coli. Both B‐ and L‐PEIs did not cause any significant permeabilization of E. coli cytoplasmic membrane. L‐PEIs induced depolarization of S. aureus membrane although B‐PEIs did not. The low MW B‐PEIs caused little or no hemolysis while L‐PEIs are hemolytic. The low MW B‐PEIs are less cytotoxic to human HEp‐2 cells than other PEIs. However, they induced significant cell viability reduction after 24 h incubation. The results presented here highlight the interplay between polymer size and structure on activity.
47.
Malitesta C Mazzotta E Picca RA Poma A Chianella I Piletsky SA 《Analytical and bioanalytical chemistry》2012,402(5):1827-1846
This review highlights the importance of coupling molecular imprinting technology with methodology based on electrochemical
techniques for the development of advanced sensing devices. In recent years, growing interest in molecularly imprinted polymers
(MIPs) in the preparation of recognition elements has led researchers to design novel formats for improvement of MIP sensors.
Among possible approaches proposed in the literature on this topic, we will focus on the electrosynthesis of MIPs and on less
common hybrid technology (e.g. based on electrochemistry and classical MIPs, or nanotechnology). Starting from the early work
reported in this field, an overview of the most innovative and successful examples will be reviewed. 相似文献
48.
D. Bucurescu Gh. Căta-Danil I. Căta-Danil M. Ivaşcu N. Mărginean C. Rusu L. Stroe C.A. Ur A. Gizon J. Gizon B. Nyakó J. Timár L. Zolnai A.J. Boston D.T. Joss E.S. Paul A.T. Semple C.M. Parry 《The European Physical Journal A - Hadrons and Nuclei》2001,10(3):255-258
High-spin states in the 96Tc nucleus have been studied with the reactions 82Se(19F,5nγ) at 68 MeV and Zn(36S,αpxn) at 130 MeV. Two γ-ray cascades (irregular bandlike structures) have been observed up to an excitation energy of about 10
MeV and spin 21-22?.
Received: 19 January 2001 / Accepted: 30 March 2001 相似文献
49.
Dijana Pei Ivana Ozimec Landek Renata Rup
i Marina Modri Iva Dapo Rudolf Trojko Mladen Merep Milan Mesi 《Journal of heterocyclic chemistry》2012,49(2):243-252
The present review focuses on dibenzo[b,f]oxepin‐10(11H)‐one ( I , X = O) and dibenzo[b,f]thiepin‐10(11H)‐one ( I , X = S) as common synthons in the efficient synthesis of various dibenzoxepino[4,5‐ and dibenzothiepino[4,5]‐fused five‐membered heterocycles: [2,3] fused thiophene ( II ), [3,4] fused thiophene ( III ), furan ( IV ), pyrrole ( V ), imidazole ( VI ), pyrazole ( VII ), oxazole ( VIII ), and thiazole ( IX ). The potential of I to be converted into reactive intermediates that readily undergo heteroaromatic annulation reactions by cyclocondensation with proper binucleophiles allows formation of a range of enumerated functionalized dibenzo[e,h]azulene [4] structures ( II , III , IV , V , VI , VII , VIII , IX ). Dibenzo[e,h]azulenes as heterotetracyclic scaffold can be exploited in further modifications to obtain compounds with altered physicochemical and biological profile. J. Heterocyclic Chem., (2012). 相似文献
50.
Milojković-Opsenica Dusanka M. Lazarević Kristina Ivačković Vojkan Tešić Zivoslav Lj. 《平面色谱法杂志一现代薄层色谱法》2003,16(4):276-279
JPC – Journal of Planar Chromatography – Modern TLC - The chromatographic behavior of nine frequently used water-soluble food dyes has been studied by TLC on RP-18 silica gel.... 相似文献