Central Composite Design for Optimized Extraction of Polysaccharides from Undaria pinnatifida

Response surface methodology was used to optimize the extraction conditions of polysaccharides from Undaria pinnatifida. The effects of three independent variables, extraction time, extraction temperature and ratio of water to raw material were investigated by a central composite design. The experimental data were fitted to a second-order polynomial equation via multiple regression analysis and also examined with the appropriate statistical methods. The adjusted coefficient of determination(R_ADj²) for the model was 0.9171. An optimum extraction yield of 30.78% was obtained when the extraction temperature was 95℃, extraction time was 4.5 h, and the ratio of water to raw material was 35(mL/g). Under these conditions, validation experiments were done and the mean extraction yield of polysaccharides was 30.79%, which was in good agreement with the predicted model value.     

凝胶排阻色谱法测定中空纤维超滤膜组件对聚乙二醇的截留率

采用凝胶排阻色谱法测定中空纤维超滤膜组件对聚乙二醇20000(PEG20000)溶液的截留率,选择Agilent PL aquagel-OH MIEXD–H8μm色谱柱,流动相为0.1 mol/L Na NO3溶液(含0.02%Na N3),流量为1 m L/min,RID检测器,柱温箱和检测器温度均为30℃。当进样体积为50μL时,方法的检出限为18.8 mg/L,定量限为49.0 mg/L。PEG20000溶液的质量浓度在60~1 000 mg/L范围内与色谱峰高呈良好的线性,相关系数r2=1.000。该方法对实际样品测定结果的相对标准差为1.31%(n=6)。将该方法的测定结果与紫外–可见分光光度计法的测量结果进行F检验和t检验,结果表明两种方法测量结果无显著性差异。采用该方法可以同时对PEG20000样品的相对分子质量及其分布进行测定,从而对选用的截留标准物质进行质量控制。     

Determination of Morphological Properties of Swellable Solids by Size Exclusion Chromatography

Many technically interesting porous solids, e.g. ion exchangers or adsorbents for catalysis, are swellable polymers, i.e. the pore structure depends on the solvent medium. A method based on exclusion chromatography, permits determination of the pore size and pore size distribution in the swollen state.—Size exclusion chromatography, also referred to as gel permeation, gel filtration, or molecular sieve chromatography, is a widely employed method for the separation of dissolved substances—mostly polymer mixtures—according to their molecular size. Porous solids are used as stationary phase. Conversely, pore sizes and other structural data can be determined by exclusion chromatography. This application requires a series of standards (polymer samples) of known molecular weight. As a simple and rapid method, it has already proven valuable for such determinations in the case of rigid solids; in the case of swellable solids, this constitutes the sole method by which the pore structure can be characterized: classical methods require dry samples.     

体积排阻色谱法测定胸腺肽分子量校准曲线条件的优化

在体积排阻色谱(SEC)法测定胸腺肽分子量校准曲线过程中,流动相中乙腈的比例对核糖核酸酶A、人胰岛素、胸腺肽α1和生长激素释放抑制因子4种蛋白的保留时间有重要影响,进而影响校准曲线的线性关系。当乙腈比例为75%时,胸腺肽分子量校准曲线线性最好,此时分子量校准方程为y=-3.138 6x+21.724,线性相关系数r2=0.988 5。4种蛋白的理论塔板数在45 783～63 345之间,拖尾因子在0.96～1.18之间,分离度在3.52～8.82之间。SEC法测定胸腺肽分子量校准曲线的液相色谱条件对4种蛋白的分离效果优异,分子量校准曲线线性良好,可用于胸腺肽制剂中高分子量物质的检测。     

高效体积排阻色谱法测定改性柑橘果胶的分子质量

改性柑橘果胶(MCP)是一种具有抗肿瘤细胞生长、侵袭和转移活性的多糖。由于多糖的分子质量对其活性有很大的影响,因而需要测定其分子质量。选择的色谱条件为：TSK G3000PWXL色谱柱,以50 mmol/L醋酸铵缓冲液为流动相,流速为0.5 mL/min,柱温为40 ℃,样品质量浓度为10 g/L,进样体积为20 μL,示差折光检测器检测。采用Pullulan糖标准品,经校正获得回归方程,通过回归方程计算得到的MCP平均相对分子质量为:Mn为21000,Mp为46000,Mw为43000,Mz为66000。MCP的多分散性指数(PD)为2。该方法具有良好的重现性,而且简便、快速,为MCP的生产工艺、质量控制和组效关系等的研究提供了实用的分析检测手段。     

Solid-Phase Extraction of Caffeine and Theophylline from Green Tea by a New Ionic Liquid-Modified Functional Polymer Sorbent

The new ionic liquid-modified polymer sorbent was developed by surface chemical modification of the synthesized polymer particles using ionic liquids. The obtained ionic liquid-modified polymer was successfully used as a special sorbent in a solid-phase extraction (SPE) process to isolate caffeine and theophylline from green tea. A comparison of different SPE cartridges using the blank polymer, C₁₈, and ionic liquid-modified polymer revealed that the highest recovery was obtained using ionic liquid-modified polymer sorbent. Quantitative analysis was carried out by using a C₁₈ column (5 µm, 150 × 4.6 mm) as an analytical column. Good linearity was obtained from 5 × 10^?4 to 0.5 mg/mL (r²>0.999) for the two analytes with relative standard deviations <4.5%.     

Characterization of River Natural Organic Matter by High-Performance Size Exclusion Chromatography

The molecular weight of natural organic matter from the Yeongsan and Seomjin Rivers and the discharge from the wastewater treatment plants were analyzed for seasonal characteristics by high-performance size exclusion chromatography. The distribution of molecular weights demonstrated relationships with microbial activity and seasonal variations with temperature. Dissolved organic carbon and total organic carbon for the Seomjin River were from 1.6 to 3.1 mg L^?1; for the Yeongsan River system, these parameters were between 2.0 and 8.0 mg L^?1. There were no significant differences between upstream and downstream organic matter. The biochemical oxygen demand (0.8–2.5 mg L^?1) for the Seomjin River was less than the chemical oxygen demand (2.9–5.0 mg L^?1). Similarly, the biochemical oxygen demand (0.9–4.6 mg L^?1) for the Yeongsan River was lower than the chemical oxygen demand (3.8–10.6 mg L^?1). The molecular weight of aromatic compounds increased as the water temperature decreased in October, whereas the molecular weights of proteins decreased as the water temperature increased. These results suggest that as microbial activity increased, natural organic matter with a smaller molecular weight may be employed as an energy source by microorganisms. As a result, seasonal variation of the water temperature may influence the distribution of organic matter in the rivers based on molecular weight and microbial activity such that the smaller natural organic matter was more readily degraded by microorganisms.     

Enthalpic Partition-Assisted Size Exclusion Chromatography: 1. Principle of Method

A novel high performance liquid chromatographic (HPLC) method viz. “enthalpic partition assisted size exclusion chromatography” deliberately combines entropic and enthalpic partition mechanisms. It enables separation of homopolymers according to their molar mass with increased selectivity, as well as discrimination of polymer species differing in their nature/composition. Enthalpic partition of macromolecules takes place between the mobile phase and the stationary “liquid” of a different chemical nature, which is immobilized within pores of an appropriate carrier (a bonded phase). The extent of enthalpic partition depends on the accessibility of bonded phase for macromolecules and on the difference of polymer solubility in the mobile phase and in the solvated bonded phase. The enthalpic partition in favor of column packing arises from better solubility of polymer solutes in the solvated stationary phase compared to the mobile phase. Macromolecules are “pushed” into the solvated stationary phase and their retention volumes (V_R) increase. In the area of high molar masses, the extent of enthalpic partition as rule raises with the increasing size of macromolecules. However, under properly chosen experimental conditions the enthalpic partition may rapidly diminish with the sample molar mass (M), likely due to the solubility changes and/or due to partial exclusion of macromolecules from the pores. As result, the corresponding retention volumes sharply drop within a narrow range of M with the increasing size of macromolecules. This results in the log M vs. V_R dependences, which resemble in their form that for size exclusion chromatography but are much more flat indicating highly selective separations of homopolymers according to their molar masses. In this way, enthalpic partition “assists” entropic partition (size exclusion). Polymer species, which do not undergo enthalpic partition, elute from the HPLC column in the conventional size exclusion mode and can be discriminated from the partitioning species. Enthalpic partition assisted size exclusion chromatography can be utilized in separation and characterization of various homopolymers, and polymer blends.     

尺寸排阻色谱对增能火药中硝化甘油分布与迁移规律的研究

用尺寸排阻色谱的方法研究了高氮量单基火药吸收硝化甘油以后硝化甘油的分布规律及加速老化过程中硝化甘油的迁移规律。结果表明,硝化甘油在高氮量单基火药中分布服从高斯分布。老化过程中,这种分布向方差增大的高斯分布变化。给出了硝化甘油迁移的速度常数,这对于增能火药的贮存和使用具有重要作用。     

体积排阻色谱法研究变性溶菌酶分子复性过程中集聚体的形成

在体积排阻色谱柱上研究了还原剂存在时脲和盐酸胍变性的3种溶菌酶溶液的复性和分离过程。当变性液中原始溶菌酶浓度大于10 g/L时,变性溶菌酶在体积排阻色谱柱上除了复性为与未变性溶菌酶出峰时间相同的复性态溶菌酶分子外,还形成了溶菌酶折叠中间体的二分子集聚体。这个结果得到了用稀释法复性时溶菌酶的蛋白电泳检测结果的支持。与稀释法复性相比较,用体积排阻色谱法复性时所形成的折叠中间体二分子集聚体的量要远远低于用稀释法所形成的集聚体的量。     

三检测体积排除色谱表征聚合物支化结构

以α-溴代异丁酸叔丁酯(t-BBiB)为引发剂,CuBr/联二吡啶为催化体系,二乙烯苯(DVB)为支化单体,采用原子转移自由基聚合反应(ATRP)经过一步加料方法和先臂后核方法分别合成不同支化结构类型的支化聚合物,同时以四官能度引发剂经ATRP合成臂数确定的星形聚合物为参照。采用三检测体积排除色谱(TD-SEC)得到Zimm相对支化因子g′与g和表征聚合物支化结构类型的指数因子ε(g′=gε)。结果表明:随支化结构类型的不同,支化结构指数因子ε表现出不同的分子量依赖特性。星状支化聚合物的ε平均值<1,而且随分子量的变化保持相对恒定;无规支化聚合物的ε平均值>1,而且其值随分子量的增加不断减小。因此,可以由三检测体积排除色谱进行分析确证聚合物的支化结构类型。     

硅胶管采样—液相色谱法测定空气中的氯氰菊酯

本文报道空气中氯氰菊酯的高效液相色谱测定方法，空气样品用硅胶管采样，经甲醇洗脱后用ＨｙｐｏｒｓｉｌＯＤＳ柱分离，紫外检测器检测，在本法的测定条件下，最低检测浓度为０．０４ｍｇ／ｍ＾３，当氯氰菊酯浓度范围为０～２５．０ｍｇ／Ｌ时，呈线性响应关系，相对标准偏差为２．４％～８．４％，本法的解吸效率为９６．８％～１００．３％，采样效率为１００％，氯氰菊酯在硅胶管中可稳定７ｄ。     

凝胶过滤色谱-多角度激光散射法测定琥珀酰明胶自由氨基修饰度

琥珀酰明胶作为血浆代用品的临床疗效与其分子量分布和修饰度密切相关。本研究利用高效凝胶过滤色谱-多角度激光散射法(HPSEC-MALLS)并结合2,4,6-三硝基苯磺酸(TNBS)衍生法,探索建立一种测定琥珀酰明胶修饰度的方法。实验利用TNBS将琥珀酰明胶衍生,通过HPSEC-MALLS测定琥珀酰明胶的分子量变化,计算出琥珀酰明胶的修饰度。实验以人血清白蛋白为模型进行了方法验证,结果表明:该方法能较好地表征人血清白蛋白在TNBS衍生过程中的分子量变化,实验值与根据其氨基酸组成计算值一致。实验在HPSEC-MALLS测定琥珀酰明胶及TNBS衍生后琥珀酰明胶分子量及分布的基础上,利用凝胶过滤色谱分子量-保留时间拟合曲线,计算得到琥珀酰明胶的自由氨基修饰度为38%。结果表明利用高效凝胶过滤色谱-多角度激光散射法结合2,4,6-三硝基苯磺酸衍生法测定琥珀酰明胶的修饰度是可行的。     

酪蛋白酶解反应复杂产物的色谱定量分析

根据酪蛋白酶解产物的高效凝胶排阻色谱(HPSEC)定性分析结果,选取不同截留相对分子质量的超滤膜对酶解产物进行截分,制得3种相对分子质量分布相对集中的区间组分;建立各组分峰面积与质量浓度之间的线性关系,由此定量计算不同反应时间的酶解产物中相应相对分子质量区间组分的质量浓度。研究表明,将膜分离方法与色谱分析相结合可实现对蛋白质、多肽等复杂体系相对精确的定量分析。     

高效凝胶排阻色谱法测定牛血清白蛋白相对分子质量及其分布

建立了一种高效凝胶排阻色谱快速测定牛血清白蛋白的相对分子质量及其分布的方法。使用凝胶色谱仪,TSKgel G3000SWXL型(300 mm×7.8 mm)高效凝胶排阻色谱柱,以0.05 mol/L磷酸盐缓冲溶液(pH 6.8)–0.3mol/L氯化钠溶液为流动相,流速为1 mL/min,DAD检测器,检测波长为220 nm,选择300~330 nm作为参比波长,信号采集时间为15 min。测得质控样牛血清白蛋白相对分子质量标准物质峰值相对分子质量的均值为7.160×104Da,与参考值的相对误差为7.76%,组间相对标准偏差为0.49%。采用该法对市售牛血清白蛋白样品的相对分子质量分布进行测试,组内相对标准偏差为0.004%~0.014%,组间相对标准偏差为1.89%。该法可以满足一般实验室对牛血清白蛋白样品的分子量分布测定的要求。     

离子排斥色谱法测定十二种有机酸的研究

研究离子排斥色谱法分离/测定有机酸。选用盐酸作淋洗液,以四丁基氢氧化铵为再生液,考察了淋洗液浓度,流量等因素对分离和测定的影响。对十二种有机酸在阴离子排斥色谱柱睥保留待业进行了系统研究,找出了柱分离有机酸的规律。在最佳色谱条件下,测定了白葡萄酒中的有机酸。     

The Direct Determination of Axial Dispersion in Size Exclusion Chromatography Based on Poissonian Chain Length Distributions

Summary A fast and straightforward method for the direct determination of _ad the extent of axial dispersion under normal working conditions is presented. The method makes use of the peak variance of Poisson distributions, which can be determined from the points of inflection. The applicability of this method is experimentally demonstrated for four series of commercially available polymer standards. Theoretical calculations and experimental results are presented that confirm that this method also works with narrow distributions which are the weighted sum of several adjacent Poisson distributions.Presented at: International Symposium on Separation and Characterization of Natural and Synthetic Macromolecules, Amsterdam, The Netherlands, February 5–7, 2003     

体积排阻色谱和激光光散射对大豆蛋白热诱导聚集体的研究

采用体积排阻色谱(SEC-HPLC)和激光光散射(LLS)研究了不同浓度和离子强度下大豆蛋白热诱导聚集体的分子量分布和粒径分布。在离子强度为0时,SEC-HPLC的结果表明,热处理后的蛋白溶液主要由3部分组成,即聚集体、中间体和未聚集部分。聚集体部分随着浓度增加而逐渐增加;LLS的结果表明:体系有不均一的粒径分布,且浓度增加时体系的平均粒径增加。上述样品在较高离子强度下加热时,SEC-HPLC和LLS的结果都证明溶液中的中间体部分逐渐消失。因此,控制浓度和离子强度可以制备不同性质的大豆蛋白聚集体。