凝胶渗透色谱技术在卷烟分析前处理中的应用进展

样品前处理对于保证结果的一致性与准确度至关重要。GPC凝胶净化系统的出现,使得前处理方便快捷,数据准确可靠。综述了凝胶渗透色谱在卷烟烟气中农残成分和特殊有害成分(苯并芘和NNK)实验方法中的应用,指出,凝胶渗透净化系统用于卷烟烟气中苯并芘和亚硝胺分析的前处理具有创新性和研究意义。     

旧报纸漆酶/介体脱墨过程中木素结构的研究

利用元素分析、功能基分析和傅里叶变换红外光谱(FTIR)对旧报纸漆酶/介体脱墨过程中木素结构的变化进行分析,并利用凝胶渗透色谱(GPC)测定木素的分子质量及其分布。元素分析及功能基分析结果表明,漆酶/介体处理后,木素C9单元分子质量降低,木素的酚羟基和甲氧基含量降低,羰基和羧基含量升高。红外光谱分析结果显示,漆酶/介体处理过程中存在木素结构的部分破坏与溶出。GPC测定结果表明,漆酶/介体处理后浆料中木素的数均分子质量、重均分子质量及多分散性均下降,说明木素受到了一定程度的降解。     

Ordered structure and thermal property of acid-modified high-amylose rice starch

High-amylose cereal starch has a great benefit on human health. Acid modification is very helpful for application of high-amylose starch in food and non-food industries. In this study, the ordered structure of acid-modified high-amylose rice starch was investigated by GPC, HPAEC, ¹³C CP/MAS NMR and XRD. Acid preferentially degraded the amylose, then A chain and short B chain of amylopectin. Relative double helix content and crystallinity both initially increased sharply and then progressively with acid hydrolysis. The relative crystallinity of starches obtained from ¹³C CP/MAS NMR was higher than that from XRD. The onset gelatinisation temperature decreased, while the peak and conclusion temperatures increased with increasing hydrolysis time. The endothermic value initially increased and then decreased with acid hydrolysis. The swelling power decreased while solubility increased after acid hydrolysis. These results add to our understanding of the effect of acid hydrolysis on the high-amylose rice starch.     

Cationic polymerization of ethylene oxide with Maghnite‐H as a clay catalyst in the presence of ethylene glycol

The activated‐monomer cationic ring‐opening polymerization of ethylene oxide, initiated with ethylene glycol and using an acid‐exchanged montmorillonite clay called Maghnite‐H⁺ as an effective catalyst, was carried out to obtain the corresponding homopolymers with narrow polydispersity ratios. The molecular weights of the obtained polymers were controlled with the feed ratio of the monomer to the initiator. The effects of the amount of the catalyst and time on the polymerization yield and viscosity of the polymers were studied. The structure was confirmed with proton nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterisation of enzymatically oxidised lignosulfonates and their application on lignocellulosic fabrics

BACKGROUND: The ‘double function’ of laccase, from the ascomycete Myceliophthora, to depolymerise/polymerise lignin was studied in this work. A lignosulfonate (LS) compound was oxidised by enzymatic action and several techniques were applied to measure the polymeric changes obtained. This study was focused on the attachment level of the oxidised LS at the flax surface. RESULTS: Modified solutions were studied in terms of surface charge. Zeta potential values obtained showed an increase of polymerisation after several days of incubation. The change in molecular weight after LS polymerisation was detected using gel permeation chromatography. An increase of 1700 Da was achieved. Fourier transform infrared and UV‐visible spectroscopy techniques were applied and the results showed an increase of the degree of polymerisation. The colour strength of flax fabrics incubated with oxidised LS solutions was also measured and an increase of K/S (K, absorption coefficient; S, scattering coefficient) after enzymatic oxidation was observed. CONCLUSION: The oxidised lignin products obtained show good potential for use in natural surface modification of textile materials containing flavonoids. These findings have important practical implications for lignocellulosic fibre coloration, where new polymers can replace harsh chemicals in the textile industry. Copyright © 2009 Society of Chemical Industry     

VDC－MA悬浮共聚树脂分子量及其分布的研究

联用宽分布ＶＤＣ－ＭＡ悬浮共聚物试样的［η］和ＧＰＣ谱图数据，确定了此共聚物在四氢呋喃溶剂中、３０℃下的Ｍａｒｋ－Ｈｏｕｗｉｎｋ常数：Ｋ＝２．５４×１０－２，α＝０．６７５７。进一步研究了单体配比、转化率、引发剂浓度以及聚合温度等因素对于分子量及其分布的影响，并建立了分子量模型。     

沥青感温性指标与沥青组成的灰关联熵分析

沥青的化学组成不同对沥青的物理性能有着不同程度的影响。为了分析这些影响因素的显著性，采用改进的灰关联熵分析法，分析了影响沥青感温性指标的因素，结果表明，这种方法克服了一般灰关联度分析方法的不足，灰熵关联度大小不受分辨系数的影响。影响老化前沥青感温性指标的主要因素是极性芳香分，环烷芳香分，以及中分子尺寸分布和大分子尺寸分布；影响老化后沥青感温性指标的主要因素是沥青的沥青胶体不稳定指数(Ic)和沥青质以及大分子尺寸分布和中分子尺寸分布。     

油田水中聚丙烯酰胺的凝胶色谱法分析

凝胶色谱分析油田水中的ＨＰＡＭ方法已在各油田广泛使用，其淋洗液是ＣＨ３ＯＨ／ＮａＨ２ＰＯ４二元体系，本分析了该体系存在的一些问题，在实际研究的基础上提出了ＮａｓＣｌ单盐淋洗液体系。本报道的以０．２ＭＮａＣｌ为淋洗液的分析体系，能够快速、准确的分析油田的ＨＰＡＭ，解决了目前以ＣＨ３ＯＨ／ＮａＨ２ＰＯ４体系作淋洗液所存在的问题。     

聚碳酸酯的分子量分布与热降解

除了用Ｍｗ，Ｍｎ和Ｍｗ／Ｍｎ表征聚碳酸酯（ＰＣ）分子量大小和分布宽度外，还采用了（Ｍｐ－Ｍ１０）和（Ｍ９０－Ｍｐ）来表征低分子量和高分子量尾端所延伸的宽度，并以两尾端的起始分子量作为参考参数。其中Ｍｐ为分子量微分分布曲线峰位分子量，而Ｍ１０和Ｍ９０则为累积分布曲线中１０％和９０％处的分子量。研究了这些参数与聚碳酸酯热降解的关系，发现除数均分子量外，高低分子量尾端部分与ＰＣ热稳定性关系密切，尤其是低分子量尾端分布状态和起始分子量大小，对ＰＣ热稳定性更为敏感。这与ＰＣ端ＯＨ基相对浓度同ＰＣ热降解率的关系相一致。