Possibilities and pitfalls in analyzing (upgraded) pyrolysis oil by size exclusion chromatography (SEC)

The applicability of size exclusion chromatography (SEC) to analyze (upgraded) pyrolysis oil samples has been studied using model compounds, pyrolysis oils and hydrodeoxygenated pyrolysis oils. The assumptions needed for the conversion of the chromatogram to the M_w-distribution were validated. It was shown that the conversion of elution volume to molecular weight (based on polystyrene calibration curves) can introduce substantial errors in the prediction of the molecular weight. The conversion of RID response to W(log M) (as plotted on the y-axis of the M_w-distribution) is based on the assumption of a compound independent RID response factor and linear response to concentration. While the latter was shown to be true within the concentration range studied, the former was not true: the RID response factor depends on the type of (upgraded) pyrolysis oil. It was shown that within a single pyrolysis oil sample, the RID response for the low molecular weight fraction was a factor 3 lower than the high molecular weight fraction. Furthermore long term column fouling can influence SEC results that cannot be corrected with regular polystyrene recalibrations.Based on the results we recommend SEC not to be used as a quantitative method for characterization (upgraded) pyrolysis oil samples, but as a tool to compare (upgraded) pyrolysis oil samples, preferably prepared using incremental operating conditions and expected to have similar molecular composition. This work has further shown that (i) the ∫UVDdv/∫RIDdv ratio can be used as an indication of the sum of the relative aromaticity and conjugated double bond content for (upgraded) pyrolysis oil, and (ii) the negative peak area appearing in the low molecular weight part of the chromatogram can be used to estimate the water content of (upgraded) oil samples.     

Recent progress in the application of analytical techniques to anticancer metallodrug proteomics

Interactions of therapeutic drugs containing metals with proteins are known to exert a great impact on the mode of action of these compounds, including drug metabolism, delivery, cell processing, and targeting. Modern analytical techniques applied to proteomic studies of metallodrugs may improve our understanding of accompanying biochemical processes, which is essential for the efficiency of treatment, the proper dosing of established metal-based cancerostatic agents, and the design and development of new drugs. Such methods basically rely on the application of mass spectrometry (or a few alternative detection techniques) for species identification, characterization, quantification, and measuring the binding parameters, directly or after separation of free parent drug and protein-bound drug fractions, using the principles of electrophoresis, chromatography or ultrafiltration.This review focuses on the development and recent advances in the field of “metallodrug proteomics” from the implementation of advanced analytical methodologies. Also addressed are emerging issues of metallodrug binding toward cellular protein targets and within real-world biological samples.     

Combination of chromatographic and chemometric methods to study the interactions between DNA strands

This work describes the combination of size-exclusion chromatography and chemometric resolution methods to study the formation of complex DNA structures from individual strands. This combined procedure has been applied to two different experimental data. Firstly, the formation of an intermolecular Watson–Crick duplex structure formed by the individual unstructured strands. Secondly, the competition between the intermolecular Watson–Crick duplex and intramolecular quadruplex structures formed by two sequences found in the hTERT gene has been studied.     

体积排阻色谱法测定低分子量肝素抗凝血因子Xa的活性

发展了一种基于体积排阻色谱测定低分子量肝素(LMWH)抗凝血活性的方法。利用肝素与抗凝血酶Ⅲ(ATⅢ)结合后可增强ATⅢ对凝血因子Xa(FXa)抑制作用的原理,通过测定加入LMWH后FXa水解其生色底物产生对硝基苯胺(pNA)这一反应的抑制程度确定LMWH的活性。首先将含有一定浓度LMWH的缓冲溶液与ATⅢ溶液混合,然后依次加入FXa和生色底物,分别孵育一段时间。底物被FXa水解,产生游离的pNA。体积排阻色谱可将小分子产物pNA与其他大分子分离开,因而可以在pNA的最大吸收波长下得到高灵敏度的测定,并且不再受其他成分的干扰。该方法重复性好,灵敏度高,极大地减少了样品的消耗量,降低了成本,并且还可进行各种复杂样品(如血浆)中LMWH抗FXa活性的监测。     

Two-dimensional liquid chromatography analysis of synthetic polymers using fast size exclusion chromatography at high column temperature

In recent years, two-dimensional liquid chromatography (2D-LC) has been used increasingly for the analysis of synthetic polymers. A 2D-LC analysis provides richer information than a single chromatography analysis at the cost of longer analysis time. The time required for a comprehensive 2D-LC analysis is essentially proportional to the analysis time of the second dimension separation. Many of 2D-LC analyses of synthetic polymers have employed size exclusion chromatography (SEC) for the second-dimension analysis due to the relatively short analysis time in addition to the wide use in the polymer analysis. Nonetheless, short SEC columns are often used for 2D-LC analyses to reduce the separation time, which inevitably deteriorates the resolution. In this study, we demonstrated that high temperature SEC can be employed as an efficient second-LC in the 2D-LC separation of synthetic polymers. By virtue of high temperature operation (low solvent viscosity and high diffusivity of the polymer molecules), a normal length SEC column can be used at high flow rate with little loss in resolution.     

中考化学实验试题与课程标准一致性的比较分析

基于“SEC”一致性分析模式,对福州、厦门、泉州的中考化学实验试题与《义务教育化学课程标准（2011年版）》中实验内容主题和认知水平要求进行一致性编码分析,总结实验题的命题特点,提出实验教学应有所侧重,命制实验题应紧扣课程标准要求。     

聚苯乙烯齐聚物的高效尺寸排除色谱的研究——Ⅰ.链长分布

用高效尺寸排除色谱以紫外吸收光度计寿检测器,测定了一个以正丁基锂引发的聚苯乙烯齐聚物的链长分布。讨论了端基对实验的紫外吸收响应以及理论的链长分布函数中各个半分散组分重量分数的影响。引进了一个端基改正因子以获得真实的重量链长分布。实验数据可以用两个Poisson分布的叠和精确描述。与单一Poisson分布的偏离相信是由于聚合反应物混合方式的变化所致。     

过敏物的高效液相排阻色谱测定

采用高效液相排阻色谱对几种过敏物质，树木花粉、寄生虫和猫狗毛萃取物进行分析，测定主要成分的分子量。结果表明，高效液相排阻色谱适合过敏物质的成分分离和分子量测定。     

Aerobic and anaerobic biodegradability of polymer films and physico-chemical characterization

Aerobic and anaerobic biodegradation of four different kinds of polymers, polylactic acid, polycaprolactone, a starch/polycaprolactone blend (Mater-bi^®) and poly(butadiene adipate-co-terephthalate) (Eastar bio^®) has been studied in the solid state under aerobic conditions and in the liquid phase under both aerobic and anaerobic conditions.Several standard test methods (ISO 14851, ISO 14853, ASTM G 21-90 and ASTM G 22-76 and NF X 41-514) were used to determine the biodegradability. To determine the efficiency of the biodegradation of polymers, quantitative (mass variations, oxygen uptake, pressure variations, biogas generation and composition, biodegradation percentages) and qualitative (variation of T_g and T_f, variation of molar mass by SEC, characterization by FTIR and NMR spectroscopy) analyses were made and materials were characterized before and after 28 days of degradation.After 28 days, the degradation of materials depends on the material and on the test conditions used. The degradation is better under aerobic conditions, in particular for Mater-bi and polycaprolactone. Nevertheless, we can notice that it is the amorphous part of the polymer which is more attacked by the micro-organisms but, after 28 days, they do not seem to cleave macromolecules inside the material: bacteria attack the surface of the polymer and seem to consume the macromolecules one after another (there is no significant variation in the molar mass and no difference between FTIR and NMR spectra before degradation and after 28 days of degradation).