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1.
The properties of styrene/butadiene copolymers obtained by conventional emulsion and miniemulsion polymerizations were studied. Thin layer chromatography with flame ionization detection was used to determine the gel fraction of the copolymer in the latex particles as a function of conversion. It was found that the gel formation began at a higher conversion in the miniemulsion polymerization when compared with that in the conventional process. Also, a lower glass transition temperature was noted at the lowest conversion sampled (~25%), implying a higher initial butadiene monomer concentration within the nucleated miniemulsion monomer droplets when compared with particles formed conventionally. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4616–4622, 2006 相似文献
2.
介绍了使用顶空-气相色谱法检测水中一氯苯的方法。该方法使氯苯分子在气液两相之间、在一定温度下达到了动态平衡。此时,一氯苯在气相中的浓度与它在液相中的浓度成正比。通过测定气相中一氯苯的浓度,即可计算出水样中氯苯的浓度。使用该方法可以直接测定水样,与国标方法相比,它无需琐碎的前处理过程,避免了实验人员与有毒有害溶剂的接触,而且测定结果稳定性较好,能够满足测定需求。 相似文献
3.
G. Pennazza C. Fanali M. Santonico L. Dugo L. Cucchiarini M. Dachà A. D’Amico R. Costa P. Dugo L. Mondello 《Food chemistry》2013
The characteristic aromatic composition of white truffles (Tuber magnatum Pico) determines its culinary and commercial value. However modifications of truffle organoleptic proprieties occur during preservation. A study of headspace of white truffles by using Electronic nose (E-nose), gas chromatography–mass spectrometry (GC–MS) and sensory analyses was performed. Truffles were stored at different conditions for 7 days: +4 and +8 °C wrapped in blotting paper or covered by rice or none of the above. Headspace E-nose measurements and sensory analyses were performed each day. Statistical multivariate analysis of the data showed the capability of E-nose to predict sensorial analysis scores and to monitor aroma profile changes during storage. Truffle’s volatile molecules were also extracted by headspace solid phase microextraction technique and separated and identified by GC–MS. Partial Components Analysis of data was performed. E-nose and GC–MS results were in agreement and showed that truffle storage in paper at +8 °C seemed to be the best storage condition. 相似文献
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5.
Sandra Biedermann-Brem Maurus Biedermann Anja Fankhauser-Noti Koni Grob Rüdiger Helling 《European Food Research and Technology》2007,224(3):309-314
A simplified method is presented for determining epoxidized soy bean oil (ESBO) in food or food simulants, such as olive oil. ESBO is transesterified with methoxide/methanol directly in the homogenated food, i.e. without prior extraction, and analyzed on a cyanopropyl or phenyl polysiloxane stationary phase without formation of dioxolanes. For most foods, flame ionization detection (FID) was appropriate, but for samples with interfering components, GC–MS was needed. Chemical ionization (CI) with ammonia is more sensitive and more selective than electron impact ionization (EI). In CI, positive and negative ion monitoring (PCI and NCI) are similar in sensitivity, but different in selectivity, i.e. the combination of the two is well suited for confirmation. Results are shown to be in agreement with on-line LC–GC–FID. 相似文献
6.
将国标GB/T3395-93测定乙烯中微量乙炔的方法进行了改进,采用大口径碳分子筛石英毛细管柱代替了原方法中的填充柱,对色谱操作条件进行了优化,该法具有分析速度快、重复性好、准确度高的特点,适用于乙烯产品及中控的分析,有较大的实用价值。 相似文献
7.
S.T.H. Sherazi Aftab Kandhro S.A. Mahesar M.I. Bhanger M. Younis Talpur Sarfraz Arain 《Food chemistry》2009
The amount of trans fatty acids (TFA) in fourteen industrially hydrogenated and deodorized oils was determined. To achieve better sensitivity 200 μm KCl cell was used in transmission Fourier transform infrared (FT-IR) spectroscopy. The results of transmission FT-IR spectroscopy were evaluated by gas chromatography (GC) with flame ionization detector (FID), and found to be comparable. All analyzed cooking oil samples had a lower trans content of 0.4–1.8%. Trans fatty acid contents of partially hydrogenated oil samples were relatively higher as comparable to those of the cooking oils. Among the samples examined, the highest level was found to be at 26.5% and 25.7% by the GC–FID and FT-IR spectroscopy, respectively. Due to harmful effects, high amounts of trans fatty acids in partially hydrogenated oils is an alarming issue for the consumer’s health and quality control authorities. 相似文献
8.
对色谱仪资源的一次有效开发 总被引:1,自引:0,他引:1
主要从生产实际出发利用我厂裂解装置现有的在线色谱仪进行改造,解决了裂解装置丙烯精馏塔因无MAPD的在线监测而造成装置能耗增加,从而有效地开发出了设备潜在资源,为我厂节约设备费用,同时对影响丙烯精馏塔产品产量的组分实现了实时监测。 相似文献
9.
建立了一次进样分析氩气中的碳、硫化物信号和质量数丰度值与比值的方法,并可获知单位氩气内不同质量数的分子、原子分布20,Ar≈3.28%;36 Ar≈0.17%;37 Ar≈0.09%;40 Ar≈62.6%;41 Ar≈33.84%;42 Ar≈0.02%。 相似文献
10.