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《Analytical letters》2012,45(7):1237-1243
Abstract This research deals with the quantitative formation of carbon dioxide in electrolytic oxidation reactions. The electrolytic reactions were run with barium peroxide to generate the superoxide anion at the anode. With the organic compounds used in these electrolytic studies we needed to develop a method where we could determine the amount of carbon dioxide liberated from these compounds with the superoxide anion. This method degasses an acidified solution with dry nitrogen, which carries the carbon dioxide to a standard solution of sodium hydroxide. Titration of the sodium hydroxide solution with standardized hydrochloric acid revealed the amount of carbon dioxide formed in the reaction after precipitation of the carbonate ions with barium chloride. Blank runs with the apparatus using anhydrous sodium carbonate produced 99% plus results of recovered carbon dioxide from the sodium carbonate. 相似文献
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Natural rubber/polycaprolactone (NR/PCL) bio-based blends with different organic peroxides were prepared using an internal batch mixer and subsequently cross-linked at 170 °C. Two types of commonly used organic peroxides, dicumyl peroxide and di(tert-butylperoxyisopropyl)benzene peroxide, were applied as free-radical initiator. Cross-linking efficiency of NR/PCL blends were investigated using oscillating disc rheometer measurements, followed by infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis and tensile testing. Total volatile organic compounds (TVOCs) emissions were determined using headspace analysis integrated with gas chromatography with flame ionization detector. Determined TVOCs emissions varying in range 21.6–52.1 μg/g and generally value of this parameter decreased with increasing content of PCL phase in studied blends or with application of more efficient di(tert-butylperoxyisopropyl)benzene peroxide as cross-linking agent. It was found that increasing of TVOCs parameter indicated deterioration of mechanical properties of NR/PCL blends, which corresponded with the changes in chemical structure and thermal properties of cross-linked NR/PCL. This confirms that evaluation of TVOCs parameter is interesting alternative for “conventional methods” to characterization of the studied bio-based blends. 相似文献
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Erzsébet P. Gere Barna Bérczi Péter Simándi Gyula Wittmann András Dombi 《International journal of environmental analytical chemistry》2013,93(7):443-450
The kinetics of the reactions of H 2 O 2 and of methyl, ethyl, tert -butyl, and cumene hydroperoxides with I m were investigated in the presence and absence of molybdate as catalyst. These results were utilized to develop an analytical method for the simultaneous determination of H 2 O 2 and organic hydroperoxides in aqueous solutions. The total amount of H 2 O 2 and organic hydroperoxides can be determined by the spectrophotometric measurement of $ {\rm I}_3^ - $ formed quantitatively during 30 min of heating at 60°C. Catalase selectively decomposes H 2 O 2 in solutions containing organic hydroperoxides. The total amount of the latter can therefore be determined iodometrically after H 2 O 2 decomposition. In the oxidation of leuco crystal violet to crystal violet by H 2 O 2 and organic hydroperoxides, horseradish peroxidase exerts similar activities in the reactions involving methyl and ethyl hydroperoxides and H 2 O 2 , but its activity is much lower with tert -butyl and cumene hydroperoxide. It was observed that acetate buffer is unsuitable for pH adjustment in this type of hydroperoxide determination in consequence of the slow oxidation of the dye in the blank solution. 相似文献
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A simplified UV spectrometric method for determination of peroxide value in thermally oxidized canola oil 总被引:2,自引:0,他引:2
The aim of present study was to develop a simple method on UV spectrometer for the determination of peroxide value (PV) of the frying oil. The basis of the PV determination was the stoichiometric reaction of triphenylphosphine (TPP) with the hydroperoxides present in frying oil to produce triphenylphosphine oxide (TPPO), which exhibits a readily measurable absorption band at 240 nm by ultraviolet region. The PV ranged between 0.15 and 11.66 meq. of active oxygen per kilogram of oil as the canola oil was heated from 0 to 12 h in the fryer at 180 °C. The proposed method was correlated with official AOCS titration method and best correlation coefficient (R2 = 0.99525) was achieved, proving that there is no significant difference in the results. Therefore, developed method could serve as an alternative to the titration method, for the determination of PV in frying oils. 相似文献
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Summary. Silica supported iron(II) was found to be an efficient catalyst for oxidation of hydrocarbons with hydrogen peroxide.
Received January 29, 2001. Accepted (revised) March 5, 2001 相似文献
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检测活性氧的荧光探针新进展 总被引:1,自引:0,他引:1
活性氧对于人体是十分重要的。然而,过量的活性氧是相当有害的,它们会对人体产生氧化损伤,导致细胞死亡。活性氧现在已经引起了化学、生物、医药等多个领域学者的浓厚兴趣,它们被认为和多种病理条件有密切的联系。由于活性氧寿命短、反应活性高,并且大部分都存在于体内很难被捕获,因此它们的分析测定是一项国际性难题。荧光探针作为活性氧的高灵敏的检测分析物,已经得到越来越广泛和深入的研究。由于每一种活性氧都有它独特的生理学活性,因此设计高选择性的,能够检测具体一种活性氧的荧光探针分子就显得十分重要。本文主要对近三年来检测单线态氧、过氧化氢、超氧阴离子和羟自由基这四种活性氧的荧光探针的研究进展进行综述,关注这类荧光探针的检测机理以及具体应用。 相似文献