Effect of oligosaccharide accumulated in the coagulation bath on the lyocell fiber process during industrial production

In this article, we investigate the effects of oligosaccharide accumulated in the coagulation bath on the lyocell fiber process during industrial production. The research method consists of three parts. First, high‐performance liquid chromatography is used to analyze the monosaccharide composition of lyocell fibers and their pulp materials to determine whether the hemicelluloses in pulp material can be precipitated from the coagulation bath and then regenerated into lyocell fibers. Second, we establish a method for measuring the total sugar mixture content in the coagulation bath, which is a necessary technique during the industrial production of lyocell fibers. Third, we study the effect of oligosaccharide accumulated in the coagulation bath on the mechanical properties and supermolecular structure of lyocell fibers through a simulation experiment. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Kinetics of the enzymatic degradation of poly(vinyl acetate) in solution

The enzymatic degradability of poly(vinyl acetate) was investigated in toluene solutions at various temperatures with hog pancreas lipase. The polymer degraded by specific scission to yield oligomeric products with a molecular weight of 700. Continuous distribution kinetics were used to determine the rate coefficients. The variation of the rate coefficients with the temperature indicated an optimum at 55°C. The p‐toluene sulfonic acid catalyzed degradation of poly(vinyl acetate) was also investigated. The degradation mechanism was random chain scission, and the energy of activation for degradation was determined from the variation of the rate coefficients with the temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2579–2582, 2003     

High‐performance liquid chromatography separation characteristics of molecular‐imprinted poly(methacrylic acid) microparticles prepared by suspension polymerization

Molecular‐imprinted poly(methacrylic acid) was synthesized with a template of retinoic acid to separate retinoid derivatives. The suspension polymerization technique was used to prepare round microparticles for high‐performance liquid chromatography (HPLC) packing column materials. The effects of the types and amounts of the dispersing agents and surfactants on the structure and size of the prepared molecular‐imprinted‐polymer particles were investigated. The separation of retinoic acid from its derivatives was more efficient when the perfluorocarbon dispersing agent was used instead of water, as the latter reduced the binding force between the objective molecules and monomers. HPLC separation features were also affected by the size and distribution of particles loaded in the column. A higher retention volume was obtained for smaller particles with a broader size distribution. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 200–212, 2005     

基于HPLC法测定大鼠体内烯啶虫胺药代动力学

[目的]建立了高效液相色谱(HPLC)测定大鼠血浆中烯啶虫胺的分析方法,研究烯啶虫胺在大鼠体内的药代动力学特征.[方法]采用C18色谱柱,以甲醇-水(体积比30:70)为流动相,检测流速为1.0 mL/min,进样体积20 μL,检测波长245 nm.通过灌胃给药后,于不同时间点下经眼眶取血,采用DAS 2.0药代动力...     

Carboxymethylation of cellulosic material (average degree of polymerization 2600) isolated from cotton (Gossypium) linters with respect to degree of substitution and rheological behavior

Carboxymethylation of cellulosic material (average degree of polymerization 2600) containing 76.5% cellulose and 23.6% xylose isolated from cotton (Gossypium) linters was studied under varying reaction conditions with respect to maximum degree of substitution (DS). The influence of reaction conditions on the apparent viscosity of the prepared derivatives was also studied. The conditions optimized were sodium hydroxide concentration 3.75M, monochloroacetic acid concentration 2.05 mol/AGU, carboxymethylation time 3.5 h, and temperature 55°C, to yield carboxymethyl cellulose of DS 0.77. Rheological studies of 1 and 2% solutions of the optimized product revealed their non‐Newtonian pseudoplastic behavior. Repeating units of the optimized product were also determined by HPLC after complete depolymerization of the polymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1477–1482, 2005     

高效液相色谱法测定蜜柚中维生素C的含量

建立一种高效液相色谱测定蜜柚中维生素C含量的方法。采用Hypersil-C18色谱柱,pH=6.0,0.05 mol/L磷酸二氢钾缓冲液∶甲醇=80∶20(v/v)作流动相。流速为1.0 mL/min,二极管阵列检测器,检测波长为254 nm。维生素C在质量浓度为20~100 mg/L范围内有良好的线性关系,线性回归方程为y=34.294x 32.619,相关系数为1.999 4,方法回收率为92.4%~107.5%,相对标准偏差小于2%。本测定方法简便,快速,准确,稳定。同样适合于测定其它水果和蔬菜中维生素C的含量。     

The influence of pH upon the hydrolysis of carboxymethylcellulose with cellulases from Trichoderma reesei

We have studied the enzymatic hydrolysis of carboxymethylcellulose (CMC) with Celluclast, a commercial preparation of cellulases deriving from Trichoderma reesei, by monitoring the variation in the concentrations of glucose and reducing sugars at a constant temperature of 50°C and different pH values. We determined both glucose and overall yield, concluding that the production of glucose directly by endoglucanase is higher than that coming from the hydrolysis of cellobiose by β‐1,4‐glucosidase and that the rate at which cellobiose is formed can be calculated via kinetic parameters that are due in the end mainly to exoglucanase activity. We observed the effect of pH upon the kinetic parameters and found that the ideal value for the hydrolysis of CMC is one of pH 4.9.     

Molecularly imprinted monolithic material for the extraction of three organic acids from Salicornia herbacea L

A molecularly imprinted monolithic material was designed and prepared by in situ thermally initiated copolymerization for the extraction of protocatechuic acid, caffeic acid, and ferulic acid from Salicornia herbacea L. Field emission scanning electron microscopy and offline solid‐phase extraction (SPE) were investigated for the characterization of this material. The extract samples were loaded onto and passed through the monolithic material; the target compounds were selectively retained on the material, whereas other interfering substances were quickly washed out. Chromatographic analysis was conducted on a C₁₈ column with ultraviolet detection at 270 nm, and an eluting solution consisting of acetonitrile, water, and acetic acid (14/86/0.5 v/v/v, pH 5.0) was used as the mobile phase at a flow rate of 0.8 mL/min. The linearity was confirmed in the concentration ranges of 0.10–200.00, 0.20–400.00, and 0.30–600.00 μg/mL for protocatechuic acid, caffeic acid, and ferulic acid, respectively, with r² greater than 0.9997. The SPE recoveries of the three organic acids ranged from 71.08 to 81.02%, and the coefficient of variation (precision) was 3.08–5.70%. This method is simple, economical, and specific and has been used successfully in the extraction of three organic acids from S. herbacea L. This cartridge can be used as a potential tool for the extraction of drugs from natural plants. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高效液相色谱法同时测定水中的9种酚类化合物

建立了高效液相色谱法同时测定水中的9种酚类化合物的分析方法。水样经固相萃取法处理后,以HypersilODS色谱柱(250mm×4.6mmi.d,5μm)为分离柱,(甲醇 乙酸)/(水 乙酸)为流动相进行梯度洗脱,流速为1.0mL/min,柱温为35℃,采用VWD检测器检测,9种酚类化合物的检出限均在0.00010mg/L以下,加标回收率在85%～130%之间。方法简便,适用于水中酚类化合物的分析。     

Chromatographic performance of monodisperse macroporous particles produced by modified seeded polymerization. II. The effect of the diluent/seed‐latex ratio

Poly(styrene‐co‐divinylbenzene)‐based monodisperse macroporous particles were obtained by a modified seeded polymerization technique. The monodisperse polystyrene particles, obtained by dispersion polymerization in sufficiently large sizes and with suitable average molecular weights, were directly used as the seed latex in the production of macroporous particles. Therefore, the number of swelling and polymerization stages in the multistage production was reduced. In the first stage, the seed particles were swollen with a diluent, dibutyl phthalate (DBP), and then with a monomer phase including styrene, divinylbenzene, and, as an initiator, benzoyl peroxide. The monodisperse macroporous particles were obtained by the repolymerization of the monomer mixture in the seed particles. The particles, having different porosity characteristics, were synthesized through variations in the dibutyl phthalate/seed‐latex (DBP/SL) ratio. Selected macroporous particle samples were slurry‐packed into stainless steel high‐performance liquid chromatography columns (300 mm long × 7.8‐mm i.d.). The separation of the protein mixture by these columns in the reversed‐phase chromatography (RPC) mode was investigated. Liquid chromatograms with high resolutions were obtained under an acetonitrile/water gradient over a wide range of flow rates (i.e., 0.5–3 mL/min), especially for the particles produced with a monomer/seed‐latex (M/SL) ratio of 3.0 mL/g. In the RPC experiments, the particles produced with an M/SL ratio of 3.0 mL/g and DBP/SL ratios of 1.0 and 1.5 mL/g exhibited better chromatographic performance than the other samples. The maximum theoretical plate number was 3500 for the particles produced with the M/SL ratio of 3.0 mL/g and DBP/SL ratio of 1.5 mL/g with albumin as the analyte. The size exclusion chromatography (SEC) calibration curves and the back‐pressure/flow‐rate relationships of the produced columns were also determined. The particles obtained with an M/SL ratio of 3.0 mL/g and a DBP/SL ratio of 1.5 mL/g exhibited the best performance in SEC applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3685–3696, 2004     

Release of dithiocarbamates into artificial sweat from latex vulcanizates: Effects of the accelerator type and storage time

The release of commonly used dithiocarbamate accelerators, namely, zinc diethyldithiocarbamate (ZDEC), zinc dibutyldithiocarbamate (ZDBC), zinc dibenzyldithiocarbamate, zinc isobutyldithiocarbamate, and zinc diisononyldithiocarbamate, into artificial sweat from natural rubber latex vulcanizates was studied. The extent of release of ZDEC was much higher than that of ZDBC or other higher homologues, as indicated by high‐performance liquid chromatography analysis. The effect of the storage time on the extent of release of ZDEC into artificial sweat from vulcanizates prepared with various amounts of ZDEC was studied. The result showed that ZDEC migrated significantly to the surface of the vulcanizates upon storage, and the amount that migrated increased with an increase in the shelf time. Moreover, the amount of ZDEC that migrated increased with an increase in the amount of ZDEC added to the latex formulations. The rate of migration, as determined from the slopes of the migration curves, was dependent on the residual ZDEC content, which in turn depended on the initial level of ZDEC incorporated during latex compounding. The analysis of the migration data showed that the migration followed a Fickian behavior, and the diffusion coefficient of ZDEC was slightly dependent on the concentration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2055–2061, 2006     

固相萃取-高效液相色谱法测定水中甲萘威

主要研究用固相萃取法富集和高效液相色谱法测定水中甲萘威的可行性,此法测定水中甲萘威的最低检测限为0.005 mg/L,相对标准偏差为RSD(n=7)≤3%,平均加标回收率为98.0%,适合于地表水及生活饮用水中甲萘威的检测。     

吸附树脂极性的高效液相色谱法测定及表征

建立了测定及表征吸附树脂极性的高效液相色谱法。DA-201极性树脂、AB-8弱极性树脂和D-101非极性树脂分别填充高效液相色谱柱,以去离子水为流动相,葡聚糖为示踪剂,流速1.0 mL/min,柱温30℃,测定树脂的极性。结果表明,正丁醇、乙醇均可作为单一探针分子,流出顺序可定性表征吸附树脂极性:DA-201极性树脂AB-8弱极性树脂D-101非极性树脂;采用乙醇/甲醇作为探针分子组,通过相对极性法计算,得到3种吸附树脂的定量极性值:DA-201极性树脂极性值100,AB-8弱极性树脂极性值18,D-101非极性树脂极性值0,相对标准偏差(RSD)均小于1.50%。方法稳定可靠,可以有效表达吸附树脂的极性。     

高效液相色谱凝胶色谱法测试高分子化合物的研究

采用了高效液相色谱仪与高效凝胶色谱柱,建立了高效液相凝胶色谱分析平台。利用其不同分子量分子在凝胶色谱中表现有不同的保留时间,使用了5种高分子单分散性标准品,根据其保留时间与分子尺寸关系,建立3次拟合校正曲线,快速、高效地获得高分子化合物数均分子量、重均分子量等多种平均分子量,指导了高分子合成方向,为高分子特性研究提供了重要手段。使用了Shodex GPC K-804L8.0 mm×300 mm(A008096)刚性凝胶柱,流动相:氯仿;示差折光检测器,异丙醇稳定性测试,RSD=0.02%,3次拟合曲线,相关系数R=0.99998%,方法稳定可靠。     

Effect of temperature and type of food simulant on antioxidant stability

Additive migration levels in food simulants from polimeric materials that are intended to be into contact with food can be affected by additive stability under the migration test conditions. In this work, the stability of some phenolic antioxidants and one oxidized phosphite antioxidant was studied in four food simulants: distilled water, 3% (w/v) acetic acid, 10% (v/v) ethanol, and the fatty food simulant olive oil, under different temperatures 5, 40, and 70°C, during ～20 days. Samples were analyzed by reversed‐phase high performance liquid chromatography (HPLC) with UV diode‐array detector. In general, antioxidants appeared to be more stable in olive oil than in the aqueous simulants. Among aqueous simulants, water and 10% ethanol allowed the highest stability of antioxidants at low temperatures. The 3% acetic acid allowed good stability for the lowest phenolic compounds even at high temperatures, but the highest molecular weight compounds decomposed very fast even at low temperatures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 656–663, 2006     

高效液相色谱法测定化妆品中依克多因的含量

建立高效液相色谱法测定化妆品中依克多因的分析方法,采用Agilent Poroshell 120 EC-C₁₈色谱柱（100 mm×3.0 mm,2.7μm）分离,以甲醇和p H为3.0的40 mmol/L磷酸二氢钠-10 mmol/L 1-庚烷磺酸钠缓冲溶液梯度洗脱,流速0.8 m L/min,柱温30℃,检测波长210 nm。采用外标法定量测定化妆品中的依克多因含量。结果表明,依克多因在5～800 mg/L的质量浓度范围内呈现良好线性关系,相关系数为0.999 8,方法的检出限和定量限分别为0.3和1.0 mg/L。该方法具有分离效率高、分析时间短、节省溶剂等优点,解决了依克多因在C₁₈色谱柱上保留弱的问题。     

白酒接触塑料中增塑剂迁移规律研究

建立了高效液相色谱法测定增塑剂DBP和DEHP的含量的方法。色谱柱为ZORBAX Eclipse XDB-C184.6×150 mm5μm,以甲醇/水为流动相,紫外检测器外标法定量。方法检出限为2 ng,回收率范围85.6%~113.5%,相对标准偏差为3.4%。结果表明,几种白酒接触塑料在乙醇溶液中增塑剂DBP和DEHP有不同程度的的迁移。其迁移量与提取时间、乙醇浓度、塑料材质等相关。     

Characterization of Imprinted Microbeads Synthesized via Minisuspension Polymerization

The properties of MIPs synthesized by minisuspension polymerization are studied. The template is cyclododecyl 2,4‐dihydroxybenzoate ( 1 ), which behaves as good mimic of the estrogenic mycotoxin zearalenone. 2‐DAEM and EGDMA are used as functional and crosslinker monomers, respectively. The synthesized particles are characterized by optical and electronic microscopy, N₂ sorption measurements, and FT‐IR spectroscopy. The molecular recognition capability of MIPs is evaluated by comparing the adsorption Freundlich isotherms of MIPs to those of the corresponding non‐imprinted polymers. It is concluded that MSP is an attractive alternative for molecular imprinting because it is easy to apply and produces high yield of spherical particles of “tunable” size with acceptable molecular recognition capabilities.

     

Synthesis of a chiral stationary phase with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] by surface‐initiated atom transfer radical polymerization and its chiral resolution efficiency

A chiral stationary phase (CSP) with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] was synthesized by the surface‐initiated atom transfer radical polymerization (SI‐ATRP) of cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)‐6‐acrylate after the SI‐ATRP of styrene on the surface of silicon dioxide supports in pyridine. The successful preparation of the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] was confirmed via Fourier transform infrared spectroscopy, field emission scanning electron microscopy, X‐ray photoelectron spectroscopy, elemental analysis, and thermal analysis. The applicability for the chiral resolution of the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐diphenylcarbamate)] was evaluated with high‐performance liquid chromatography with 10 racemates under various mobile phases of hexane/alcohol, hexane/tetrahydrofuran (THF), and hexane/chloroform. The results show that the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐diphenylcarbamate)] could be used in THF and chloroform as eluents. The chiral resolutions of the commercial Chiracel OD, the CSP with cellulose 2,3‐bis(3,5‐dimethylphenylcarabmate), and the CSP with poly[styrene‐b‐cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate)] prepared by SI‐ATRP were examined. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高效液相色谱法测定乙酰丙酮含量

探索了建立高效液相色谱法测定乙酰丙酮含量。其方法为:采用岛津LC-10AT型高效液相色谱仪,使用Shi madzu VP-ODS(150 mm×4.6 mm,4.6μm)色谱柱,以甲醇(100%)作为流动相,流速0.3 mL/min,检测波长274 nm,柱温30°C。结果为乙酰丙酮进样量在15.62～156.2 ng范围内与峰面积线性关系良好(r=0.999 9);乙酰丙酮平均回收率(n=6)为100.02%;相对标准偏差(RSD)为1.44%。该方法简便、快速、准确、重复性好,可用于乙酰丙酮含量测定。