SIZE EXCLUSION CHROMATOGRAPHIC COLUMN PACKED WITH REGENERATED CELLULOSE GELS

Microporous regenerated cellulose gel particles were prepared by mixing cellulose cuoxam with silk fibroin as pore former, and the mean pore size and pore volume of the particles were 525 nm and 7.27 mt g(-1), respectively. A preparative size-exclusion chromatography (SEC) column (550 mm x 20 mm) packed with the cellulose gel particles was used for the fractionation of two polysaccharides Dextran 07 (M-W = 7.14 x 10(4), d = 1.7) and Dextran 50 (M-W = 50.5 x 10(4), d = 3.8) in water phase. The fractionation range of the stationary phase covered M, from 3 x 10(3) to 1.1 x 10(6). The daily throughput was 2.9 g for Dextran 07 (D07) and 4.3 g for Dextran 50 (D50) with a flow-rate of 1.5 mt min(-1). The fractions obtained by using the SEC were analyzed by an analytical SEC combined with laser light scattering (LLS), and the polydispersity indices of fractions for Dextran 07 and Dextran 50 were determined to be 1.34-1.57 and 1.53-3.36, respectively. The preparative SEC is a simple, rapid, and suitable means not only for the fractionation of polysaccharides in water but also for other polymers in organic solvents.

Purification of a Choleragenoid by Ion-exchange Chromatography

Abstract: Choleragenoid was obtained in pure form by ultra-filteration and fractionation on cationexchange resin-phospho-cellulose column. The choleragenoid was highly pure as judged by the electrophoresis of isoelectric focusing,immunization and SDS-gel electrophoresis.The results of test are thesame as that of the standard choleragenoid.Keywoeds:choleragenoid; vibrio cholerae; purification;ion-exchange; chromatography

Conversion of Cellulose to 5-Hydroxymethylfurfural in Water- Tetrahydrofuran and Byproducts Identification

Conversion of cellulose into platform chemical 5-hydroxymethylfurfural （HMF） in water-tetrahydrofuran （THF） co-solvents under acidic condition was studied. 38.6% of HMF was obtained with low cellulose concentration of 2.4wt%, but levulinic acid （LA） and solid humins became the main products with high cellulose concentration. The soluble byproducts were analyzed by high performance liquid chromatography/multiple stage tandem mass spec-trometry, and chemicals with formula of C9H16O4、 C10H14O4、 C11H12O4、C12H10O5 and C12H16O8 were detected. THF could participate in the reaction via ring-opening into 1,4-butanediol followed by esterification with LA into C9H16O4 or etherification with HMF into C10H14O4. C11H12O4 was formed by esterification of HMF with LA, C12H10O5 was formed by self-etherification of HMF, while C12H16O8 was formed by acetalization of HMF with glucose. Self-etherification of HMF and etherification of HMF with 1,4-butanediol were identified as two main side reactions.

Effect of Single-walled Carbon Nanotubes on Cellulose Phenylcarbamate Chiral Stationary Phases

Single-walled carbon nanotubes（SWNTs） have a high adsorption ability and nanoscale interactions. Cellulose trisphenylcarbamates possess high enantioseparation ability in high-performance liquid chromatography（HPLC）. Single-walled carbon nanotubes mixed with cellulose trisphenylcarbamate are coated on the silica gel as chiral stationary phases and higher enantioseparation factors are obtained. After a single-walled carbon nanotube is linked to the 6-pesition of cellulose 2,3-bisphenylcarbamate, its enantioseparation resolution increases compared to that of the cellulose trisphenylcarbamate. It is the first time that SWNTs have been applied to enantioseparation. The results indicate that the single-walled carbon nanotubes are good promoters of chiral recognition. This method can be used to improve the enantioseparation efficiency of the polysaccharide chiral stationary phases.

Modified DIX model for ion-exchange equilibrium of L-phenylalanine on a strong cation-exchange resin

L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purification of L-phenylalanine based on ion-exchange chromatography. In this work, the equilibrium uptake of L-phenylalanine on a strong acid-cation exchanger SH11 was investigated experimentally and theoretically. A modified Donnan ion-exchange （DIX） model, which takes the activiW into account, was established to predict the uptake of L-phenylalanine at various solution pH values. The model parameters including selectivity and mean activity coefficient in the resin phase are presented. The modified DIX model is in good agreement with the experimental data. The optimum operating pH value of 2.0, with the highest t-phenylalanine uptake on the resin, is predicted by the model. This basic information combined with the general mass transfer model will lay the foundation for the prediction of dynamic behavior of fixed bed separation process.

Interfacial Properties of Ethyl Cellulose/Cellulose Acetate Blends by HPLC

The high performance liquid chromatography method (HPLC) with ethyl cellulose/cellulose acetate (EC/CA) blends and EC as column packing material, and small molecular weight compound as probe molecules was employed to measure the retention volume (VR) and equilibrium distribution coefficient (K) of both inorganic and organic solutes. The interfacial separation properties of EC/CA blends were characterized by the HPLC data. The effects of the blends on the interfacial adsorption properties, hydrophilicity, affinity, polar and non-polar parameters of EC membrane materials were studied subsequently. The research results indicate that the interfacial adsorption properties and hydrophilicity of EC have been improved by solution blending with CA. The alloys are superior to EC in the separation efficiency for non-dissociable polar organic solute. The EC/CA alloy (80:20, ω) is suitable for desalting and desaccharifying.

Suitability of Steric Mass-action Model for Ion-exchange Equilibrium of Micromolecule

The steric mass-action (SMA) model has been widely reported in the literature for ion-exchange and metal-affinity interaction adsorption equilibrium of biomacromolecules. In this paper, the usefulness of SMA model is analyzed for describing micromolecule ion-exchange equilibrium onto cation exchangers, CM Sephadex C-25 and Streamline SP. Batch adsorption experiments with ephedrine hydrochloride as a model adsorbate are carried out to determine the model parameters, that is, steric factor, characteristic charge and equilibrium constant. The result shows that the SMA model parameters of micromolecule cannot be obtained using the nonlinear least-square fitting method as protein's due to the remarkable difference between the molecular mass and dimension of micromolecule and protein. It is considered that the small size of the adsorbates dealt with in this study justifies the neglect of steric hindrances arising from adsorbate bulkiness. Thus, the three-parameter SMA model is reduced to two-parameter one (i.e., steric factor is equal to zero) for describing micromolecule ion-exchange equilibrium. It is found that the equilibrium constant for CM Sephadex C-25 increases with increasing ionic strength, while the equilibrium constant for Streamline SP shows an opposite trend. This is probably due to the remarkable difference between the physicalpro perties of the two adsorbents. Then, the relationship between the equilibrium constant and ionic strength is described by an expression. The computer simulations show that, the theoretical model with the correlation is promising in the prediction of micromolecule adsorption decrease with increasing ionic strength in a wide range of salt concentration.

Structure Elucidation of Hydroxypropyl Cellulose Homogenously Prepared from NaOH/Urea Aqueous Solution

Hydroxypropyl celluloses(HPC) were homogenously synthesized by the reaction of cellulose with propylene oxide in NaOH/urea aqueous solution.Water-soluble HPC with molar degree of substitution(MSNMR) in the range of 0.52~0.78 was prepared from microcrystalline cellulose,cotton linters,and spruce sulfite pulp.The structure of the HPC samples was characterized by means of FT-IR,NMR,gas chromatography(GC),and size exclusion chromatography(SEC) analyses.Three types of cellulose samples with different molecular weights were found to dissolve well in the NaOH/urea solvent with no obvious differences in reactivity and regioselectivity.The relative reactivity of hydroxyl groups in the glycosyl unit was in the following order:O-6>O-2>O-3.In addition,the results of the study indicated that the tandem reaction during hydroxypropylation could be ignored.

尼龙-6改性纤维素纸结合高效液相色谱技术检测水中7种酚类化合物

以纤维素纸张为基底,在甲酸中通过原位合成法在纤维素纸表面中引入尼龙-6,获得改性纤维素纸,并分析了改性纤维素纸的形貌和结构。利用改性纤维素纸作为固相萃取处理材料富集浓缩水体中的7种酚类化合物,建立了一套改性纤维素纸―高效液相色谱法检测水环境中7种酚类化合物的实验方法,并用于实际样品的检测,结果表明在3种实际样品中7种酚类化合物回收率的范围为59.0%~74.7%,其中检出限(LOD)范围为0.5~4.5 ng/L,定量限(LOQ)范围为6.9%~13.8%,基质效应为96.1%~104.6%,改性纤维素纸在分析与检测领域具有较好的应用前景。

常压下酸催化多元醇液化纤维素反应机理的研究

开发农林废弃物高值化利用路径与“深入推进能源绿色低碳转型”国家重大战略需求高度契合。实验探索农业废弃物玉米秸秆中纤维素组分常压酸(H3PO4)催化多元醇[丙二醇(PG)与二甘醇(DEG)混合液]液化反应路径为研究目标,了解酸催化多元醇作用条件下的木质生物质液化反应机理。采用傅里叶红外光谱(FTIR)、凝胶渗透色谱(GPC)、核磁共振波谱(NMR)及热重分析(TGA)对不同反应时间下纤维素液化所得生物油的化学基团、分子量及其分布、分子结构、热解等进行了分析。FTIR检测表明,不同反应时间所得生物油具有相似FTIR特征;液化初期,纤维素降解生成了较多的烃类、醚类和含羰基化合物;液化后期,纤维素中的糖类降解产物、羟基或烯烃与PG/DEG反应生成了难溶于1,4-二氧六环的有机物。GPC分析表明,随着液化的进行,纤维素分子链发生断裂程度加剧,降解生成低分子量(LMW)物质越来越多,降解反应占主导地位;而当反应时间达到某一值时,其降解产物与PG/DEG发生聚合反应产生越来越多的大分子量物质,使生物油的分子量不再降低,即聚合反应占主导地位。^(1)H-和^(13)C-NMR表明,纤维素在液化作用下发生降解使得分子链断裂,仍保留了部分葡萄糖单元结构;随着液化反应的进行,这些结构单元再次发生转化产生LMW化合物;反应继续进行时,这些产物之间或与PG/DEG之间可进行聚合反应,形成结构趋于一致、性质逐渐稳定的新物质。TGA分析结果:生物油中含有70%~85%碳数小于25和5%~10%碳数高于25的化合物,最终残炭率随着反应时间的延长先降低再升高。实验通过研究纤维素在多元醇液化过程中的结构变化,揭示其液化的反应历程,为探索秸秆全组分的液化机理奠定理论基础。

液相色谱-原子荧光光谱法测定再生纤维素食品包装材料无机砷方法研究

目的对再生纤维素食品包装材料中无机砷含量提取和检测条件优化。方法通过优化浸提体积、提取方式、温度及时间等参数,得到最佳试验条件,以液相色谱进行分离,以原子荧光光谱仪进行测定。结果该方法使4种不同砷形态化合物在10 min内有效分离,且各自的线性关系良好(r>0.999)。添加3个不同浓度As(Ⅲ)与As(Ⅴ)的样品,回收率为85.9%~105.3%,相对标准偏差为2.4%~6.3%,方法检出限为0.02 mg/kg。结论该方法简便、快速、灵敏度高、精密度好,可以满足对再生纤维素食品包装材料中无机砷含量检测需求。

Obtaining Bacteriocins by Chromatographic Methods

Bacteriocins are a large group of chromosome or plasmid-encoded and ribosomally synthesized low-molecular-weight (2 to 6 kDa) antimicrobial and amphiphilous peptides produced by Gr+ or Gr- bacteria [1]. Their low toxicity as well as the absence of allergenicity and reactogenicity is confirmed by testing selected bacteriocins [2] [3]. Bacteriocins can be widely used as preservatives and antibiotic alternatives in medicine. Nisin, a Streptococcus lactis-derived bacteriocin, has been in practice in food industry for a long time. A relevant product contains about 2.5% of nisin. For medical use (e.g., when injected into the blood stream), highly purified drugs are required. However, the yield of bacteriocins accounts for no more than a few percents from the total activity in the culture liquid. In this paper, we propose methods (by example of two B. subtilis strains), allowing to increase the yield up to ~80%. It is believed that other bacteriocins may be purified by these methods and with the same yield.

基于纤维素基固相萃取材料分析尿液中的苯丙胺毒品

对纤维素进行酸酐改性,制备了纤维素基萃取材料(Cell-COOH),用于尿液中苯丙胺的富集,并建立了基于该材料的固相萃取-高效液相色谱联用技术,用于尿液中苯丙胺的测定。采用FTIR、XRD、SEM、XPS对Cell-COOH结构进行了表征;优化了固相萃取条件,并对其特异性、抗干扰能力、可重复利用性及方法的可行性进行了测试和验证。结果表明,Cell-COOH表面含有羧基官能团,对苯丙胺具有较好的吸附能力;在其他滥用药物和共存离子的干扰下,该法表现出良好的特异性和抗干扰能力,在第7次使用时萃取回收率仍保持在92%以上。在pH为8,萃取剂Cell-COOH用量为0.50 g/L,萃取时间为30 min,洗脱剂为体积分数0.8%的盐酸、洗脱剂用量为0.08L/g(萃取剂)、洗脱时间为20min的最佳条件下,该法的线性范围为0.01~2.00mg/L(R^(2)=0.9973),检出限为2.5μg/L,定量限为8.0μg/L。使用Cell-COOH对实际尿液中的苯丙胺进行了萃取,其萃取回收率为74.41%~82.14%,相对标准偏差(n=3)为2.32%~6.85%。

纤维素临氢水解反应产物的高效液相色谱分析

采用高效液相色谱法测定纤维素临氢水解反应产物,建立了定量分析的方法和回归方程。考察了不同流动相组成、流速、精密度和回收率对分析效果的影响。结果表明,较适宜的分析条件为流动相乙腈∶水为3∶1,流速为1 mL/min。在此分析条件下,纤维素临氢水解反应产物的峰面积与主要成分乙二醇、1,2-丙二醇和丙三醇标准品的线性关系良好,相关系数在0.99以上,精密度实验中乙二醇、1,2-丙二醇和丙三醇的RSD值在1.2%~1.9%之间,重复性实验乙二醇、1,2-丙二醇和丙三醇的RSD值在1.4%~1.6%之间,加标回收率实验的回收率在98.44%~102.55%之间,所建立的方法比较可靠。

高效液相色谱-电雾式检测器测定氨溴特罗口服溶液中羟乙基纤维素含量

目的:建立测定氨溴特罗口服溶液中羟乙基纤维素的高效液相色谱-电雾式检测器(HPLC-CAD)方法。方法:采用TSKgtl G2000SW(60 cm×7.5mm,10μm),以10 mmol·L^(-1)乙酸铵(pH 4.5)-乙腈=95∶5为流动相,柱温:30℃,流速:1.0 mL·min^(-1),电雾式检测器的蒸发温度为50℃。结果:该方法对羟乙基纤维素专属性良好,精密度、平行性和回收率均满足分析要求,峰面积线性关系良好(r>0.995)。结论:新建方法专属性好、操作简便,可以满足氨溴特罗口服溶液中羟乙基纤维素分析的要求。

热脱附-气相色谱质谱联用法分析3种活性炭添加对燃香产品香味的缓释作用

以不同比表面积的椰壳活基与大麻杆基活性炭作为燃香产品Ⅰ~Ⅲ型添加剂,采用热脱附-气质联用法对燃香样品进行香气缓释实验,平行测定6次,其总峰面积及主要化合物峰面积RSD值均小于10%,重复性较好。结果表明,Ⅰ~Ⅲ型活炭对自然放置状态的燃香样品具有香味缓释功能,但缓释能力并不与其比表面积呈正比;同时,Ⅰ~Ⅲ型活性炭对点燃状态下的燃香样品香味发散有加强作用,对有毒有害物质有削弱能力,但作用能力可能与活性炭本身的纤维素含量相关。

醋酸纤维素全配方包衣预混剂中聚乙二醇3350含量测定方法验证

目的确认本方法适合于醋酸纤维素全配方包衣预混剂中聚乙二醇3350的含量检测要求;方法采用液相色谱法,对样本进行检测并对检测结果进行分析;结果聚乙二醇3350线性关系理想范围为0.2~2mg/mL,样本的平均回收率为102.1%,RSD为0.72%;结论在用于醋酸纤维素全配方包衣预混剂中聚乙二醇3350的检测时,液相色谱法操作简便、灵敏度高、重现性好、回收率高等优势,能够满足实验要求。

Determination of the solubility parameter of cellulose acrylate using inverse gas chromatography

The solubility parameters of cellulose acrylate substituted degree 2.12(CEA) have been calculated from the measured retention data by inverse gas chromatography at various temperatures. The weight frac-tion activity coefficients of the solvents at infinite dilution(Ω1∞),the Flory-Huggins thermodynamic in-teraction parameters between CEA and solvents(χ 1∞2),the excess molar heats of mixing(△H1s),the par-tial molar heats of mixing at infinite dilution(△H1∞),the solubility parameters of solvent(δ1),and the solubility parameters of CEA(δ2),were calculated at various temperatures. The δ2 of the CEA was 17.32,18.00,18.13,18.54,19.39 at 55,60,65,70 and 75℃,respectively.

异丙甲草胺立体异构体在高效液相色谱手性固定相上的分离

在Pirkle“刷型”(S ,S) Whelk O1手性柱和涂敷型纤维素三 (3,5 二甲基苯基氨基甲酸酯 ) (CDMPC)手性柱上 ,对异丙甲草胺立体异构体进行了分离。在 (S ,S) Whelk O1手性柱上考察了不同体积比的正己烷 异丙醇流动相对分离的影响 ,发现当异丙醇含量降低时有利于异构体的分离 ;在CDMPC手性柱上考察了正己烷中醇类改性剂的种类和浓度对分离的影响 ,发现醇含量降低时和采用大体积的醇时有利于异构体的分离。异丙甲草胺的对映异构体之间在 (S ,S) Whelk O1手性柱上获得了分离 ,在CDMPC手性柱上分离出了异丙甲草胺 4个异构体中的 3个。同时测定了富S 异丙甲草胺异构体中S 异构体的过量值 (EE) ,本方法可用于富S

Large_scale Isolation and Purification of R_phycoerythrin from Red Alga Palmaria palmata Using the Expanded Bed Adsorption Method

R-phycoerythrin, a light-harvesting protein in some marine algae, and can be widely used in medicine, was isolated and purified from a red alga, Palmaria palmata (Lannaeus) Kuntze, using the streamline column (expanded bed adsorption) combined with ion-exchange chromatography. Because the crude extract was applied to the column upwardly, the column would not be blocked by polysaccharides usually very abundant in the extract of marine alga, this kind of blockage could hardly lie overcome in ordinary chromatographic column. After applying the crude extract containing 0.5 mol/L (NH4)(2)SO4, (NH4)(2)SO4 solution of different concentrations (0.2 mol/L, 0.1 mol/L and 0.05 mol/L) was used to elute the column downwardly and the eluates were collected and desalted. The desalted eluates were then applied onto all ion-exchange chromatographic column loaded with Q-sepharose for further purification of the R-phycoerythrin. Through these two steps, the purity (OD565/OD280) of the R-phycoerythrin from P. palmata was up to 3.5, more than 3.2, the commonly accepted criterion for purity, and the yield of the purified R-phycoerythrin could reach 0.122 mg/g of frozen P. palmata, much higher than that of phycobiliproteins purified with the previous methods. The result indicated that the cost of R-phycoerythrin will drop down with the method reported in this article.