Comparison of two methods for extraction of volatiles from marine PL emulsions

The dynamic headspace (DHS) thermal desorption principle using Tenax GR tube, as well as the solid phase micro‐extraction (SPME) tool with carboxen/polydimethylsiloxane 50/30 µm CAR/PDMS SPME fiber, both coupled to GC/MS were implemented for the isolation and identification of both lipid and Strecker derived volatiles in marine phospholipids (PL) emulsions. Comparison of volatile extraction efficiency was made between the methods. For marine PL emulsions with a highly complex composition of volatiles headspace, a fiber saturation problem was encountered when using CAR/PDMS‐SPME for volatiles analysis. However, the CAR/PDMS‐SPME technique was efficient for lipid oxidation analysis in emulsions of less complex headspace. The SPME method extracted volatiles of lower molecular weights more efficient than the DHS method. On the other hand, DHS Tenax GR appeared to be more efficient in extracting volatiles of higher molecular weights and it provided a broader volatile spectrum for marine PL emulsion than the CAR/PDMS‐SPME method.     

Application of Headspace Solid-Phase Microextraction and Gas Chromatography for the Analysis of Furfural in Crude Palm Oil

Processing of vegetative material containing pentoses has been shown to result in the formation of furfural. Furfural exhibits a spectrophotometric absorption peak at 518 nm when complexed with aniline acetate. Headspace solid-phase microextraction (HS-SPME) method has been successfully used to confirm the presence of furfural in crude palm oil (CPO). Solid phase microextraction (SPME) fiber composed of divinylbenzene/Carboxen/polydimethylsiloxane (DVB/PDMS/CAR) was used to absorb the volatiles in the headspace of the oil. The isolated compounds from the fiber was desorbed and separated on a capillary polar column of a gas chromatograph. Response surface methodology (RSM) was used to optimize the SPME fiber condition for maximum absorption of furfural from CPO. The optimized temperature and time for furfural extraction onto the SPME fiber are 70 °C for 40 min. Oils obtained from the mill were found to contain between 2 and 13% furfural.     

Preparation of molecularly imprinted polymers on the surface of optical fiber for HS-solid-phase microextraction of phenol

Optical fiber was modified with 3-(methacryloxy)propyltrimethoxysilane and copolymerized with the vinyl end groups and methacrylic to graft a thin layer of molecular imprinted polymer on the surface of the fiber without surface controlling. The modified fiber with phenol-imprinted polymer was coupled with gas chromatograph for headspace solid-phase microextraction (HS-SPME) of phenol. The extraction properties were examined using the SPME device coupled with a gas chromatograph–flame ionization detector (FID). Effects of extraction parameters, namely pH, exposure time, sampling temperature, and salt concentration, on extraction efficiency were also studied.     

Investigating the Potential Use of Chemical Biopsy Devices to Characterize Brain Tumor Lipidomes

The development of a fast and accurate intraoperative method that enables the differentiation and stratification of cancerous lesions is still a challenging problem in laboratory medicine. Therefore, it is important to find and optimize a simple and effective analytical method of enabling the selection of distinctive metabolites. This study aims to assess the usefulness of solid-phase microextraction (SPME) probes as a sampling method for the lipidomic analysis of brain tumors. To this end, SPME was applied to sample brain tumors immediately after excision, followed by lipidomic analysis via liquid chromatography-high resolution mass spectrometry (LC-HRMS). The results showed that long fibers were a good option for extracting analytes from an entire lesion to obtain an average lipidomic profile. Moreover, significant differences between tumors of different histological origin were observed. In-depth investigation of the glioma samples revealed that malignancy grade and isocitrate dehydrogenase (IDH) mutation status impact the lipidomic composition of the tumor, whereas 1p/19q co-deletion did not appear to alter the lipid profile. This first on-site lipidomic analysis of intact tumors proved that chemical biopsy with SPME is a promising tool for the simple and fast extraction of lipid markers in neurooncology.     

Conducting rubberlike copolymer–carbon fiber composites

Electrically conductive rubberlike copolymer–carbon fiber composites have been prepared by either a solution method or a concentrated emulsion method. In the former procedure, carbon fibers were introduced with stirring in a copolymer–toluene solution, and the polymer–fiber composites were precipitated by extracting the solvent with methanol. In the latter procedure, a pastelike concentrated emulsion of copolymer–toluene solution in an aqueous solution of sodium dodecylsulfate (SDS) was first formed, and the carbon fibers were mechanically blended with the concentrated emulsion. The polymer–carbon fiber composites were precipitated by extracting the toluene and water with methanol. Four kinds of rubberlike copolymers have been used: styrene/ethylene–butylene/styrene triblock copolymer (SES), styrene/butadiene/styrene triblock copolymer (SBS), ethylene/propene/ethylene triblock copolymer (EPE), and ethylene/vinylacetate copolymer (EVA). Short (L = 0.1 mm)- and medium (L = 5 mm)-length carbon fibers were employed. The composites were hot-pressed in a Laboratory Press to form a sheet. The effects of the two methodologies on the electrical conductivity and mechanical properties of the sheets were investigated by changing the type of polymer, the size of the carbon fibers, the volume fraction of the carbon fibers in the composites, and the hot-pressing temperature. Composites with electrical conductivities in the range of 5–14 S/cm, tensile strengths in the range of 10–17 MPa, and elongations at break point larger than 200% were obtained. The conductivities of the composites prepared with the short fibers were by two orders of magnitude smaller than those prepared with medium-size fibers. © 1994 John Wiley & Sons, Inc.     

一种新型固相微萃取涂层的研制与应用

制备了作为固相微萃取（SPME）涂层的硅酮弹性体一聚氨酯共混物,考察了该共混物的物理性能;制作了SPME装置;用顶空萃取法对水中芳香化合物进行了萃取实验。实验结果表明：涂层最高使用温度为240℃;萃取头表面平整,涂层内硅（Si）元素分布均匀;涂层对水中苯、氯苯、硝基苯萃取的色谱峰高与浓度线性关系良好且灵敏度高,各自的检出限分别为4．22μg／L、9．36μg/L和、5．01μg/L,结果令人满意。     

The composition of corn oil obtained by the alcohol extraction of ground corn

All commercial corn oil is obtained by the hexane extraction of corn germ. The chemical composition of commercial corn oil has been well characterized. This study was under-taken to quantitatively evaluate the lipid composition of corn oil obtained by the ethanol extraction of ground, whole corn kernels. When corn oil was obtained by extracting ground corn kernels (ground corn) with polar or nonpolar solvents, the resulting corn oil contained much higher levels of hydroxycinnamate steryl esters (≈0.3%) than those found in commercial hexane-extracted corn (germ) oil (≈0.02%). The levels of valuable tocopherols and tocotrienols were also significantly higher in kernel oil than in traditional corn germ oil. We previously reported that when corn oil was obtained by extracting corn kernels with polar solvents, the oil contained two polyamine conjugates, diferuloylputrescine and p-coumaroyl feruloylputrescine. In the current study, when ground corn was extracted with ethanol, the resulting corn oil contained about 0.5% diferuloylputrescine and about 0.2% p-coumaroyl feruloylputrescine. This is the first study to quantify these unique compounds in corn oil extracted by new techniques. This compositional information is important because this new oil is being considered for human food use.     

Review of thermally point‐bonded nonwovens: Materials,processes, and properties

Recent research on all aspects of thermally point‐bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding, and the mechanical properties of the resultant nonwoven materials. This article will review (1) how the thermal bonding process transforms the material properties of feed fibers, (2) the implications for material selection, and (3) the resultant failure properties of the bonded nonwoven. The formation of a bond during thermal bonding follows in sequence through three critical steps: (1) heating the web to partially melt the crystalline region, (2) reptation of the newly released chain segments across the fiber–fiber interface, and (3) subsequent cooling of the web to re‐solidify it and to trap the chain segments that diffused across the fiber–fiber interface. The time scales for these processes closely match commercial practice. In addition, adequate pressure is required to compress the fibers that form the bond spots and enhance heat transfer to these fibers. However, pressures typically used in commercial practice are insufficient to increase the melting temperature significantly or to produce significant heating due to compression of the fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

顶空固相微萃取-气相色谱法测定水中四氢呋喃的研究

以顶空固相微萃取为样品的前处理手段,结合气相色谱,以氢焰离子化检测器测定水样中的四氢呋喃.通过对萃取头类型、萃取时间和温度、解吸温度和时间等影响萃取效率的因素的研究,获得了优化的试验条件.在优化条件下,方法的线性较好,样品的加标回收率为97.5%-106.7%,相对标准偏差为3.2%-4.9%,检出限可以达到0.10μ...     

Headspace Analysis in Chemical Ecology: Effects of Different Sampling Methods on Ratios of Volatile Compounds Present in Headspace Samples

The effects that different headspace sampling methods have on the analysis of the ratios of compounds present in the headspace of a synthetic mixture and a biological sample were evaluated using the following methods: solid-phase microextraction (SPME), a syringe, and the porous polymers Porapak Q, Tenax TA, and Hayesep Q (thermal and solvent desorption). The performance of each method was only evaluated for a certain sampling period and under given experimental conditions. The test mixture comprised pentan-3-ol, 4-penten-1-ol, (E)-2-hexenal, hexan-1-ol, heptanal, (1S,5S)-(–)--pinene, 6-methyl-5-hepten-2-one, hexyl acetate, (R)-(+)-limonene, and undecane. SPME gave significantly different ratios of pentan-3-ol, 4-penten-l-ol, hexan-1-ol, heptanal, (1S,5S)-(–)--pinene, 6-methyl-5-hepten-2-one, hexyl acetate, limonene, and undecane compared with the other methods. No significant differences were observed between the syringe and the porous polymers or between the three different porous polymers used. The method of release of the trapped analytes from the polymers, thermal or solvent desorption, did not affect the ratios of compounds. The effects that different sampling methods have on the ratios of compounds present in the headspace of a biological sample, ripe banana, were evaluated. The headspace was sampled using SPME and the porous polymers Porapak Q and Tenax TA (thermal desorption). The following compounds were identified in the headspace of ripe bananas: 2-methylbutyl acetate, pentyl acetate, 2-methylbutyl propanoate, butyl butanoate, and pentyl butanoate. SPME gave significantly different ratios of 2-methylbutyl acetate, pentyl acetate, butyl butanoate, and pentyl butanoate when compared to Porapak Q and Tenax TA. No significant differences on the ratios of compounds present in the headspace of ripe banana were observed when the two polymers were compared. The use of different sampling methods in headspace analysis of biological samples is dicussed.     

草珊瑚总黄酮的超声提取工艺研究

研究了超声法提取草珊瑚总黄酮的工艺.影响草珊瑚总黄酮提取率的主要因素是乙醇体积分数,其次是提取次数,提取时间和液料比对提取率影响不显著.正交实验确定草珊瑚总黄酮的最佳超声提取条件是:40%乙醇,液料比10∶1,提取时间40 min,提取3次.此条件下总黄酮得率为8.53%.超声提取法具有短时高效的优点,适合于草珊瑚总黄酮的提取.     

正交设计法优选杜鹃花中总黄酮的提取工艺

为确定提取杜鹃花中总黄酮的最佳工艺条件。以用分光光度法测定得到的总黄酮含量为指标,采用正交试验设计,分别考察乙醇冷浸、回流和超声提取对提取率的影响,并与乙醇索氏提取法比较。结果得到在不同的乙醇提取工艺中,总黄酮含量高低顺序为回流法≈索氏提取法〉超声法≈冷浸法。由此知提取杜鹃花总黄酮的最佳工艺条件为11倍量60％乙醇,水浴回流提取2次,每次1．5h。     

Mixed hemimicelle solid-phase extraction based on magnetic carbon nanotubes and ionic liquids for the determination of flavonoids

A novel mixed hemimicelles solid phase extraction (SPE) based on magnetic carbon nanotubes (MCNTs) and ionic liquid (IL) is developed for the simultaneous extraction and determination of trace flavonoids in spiked human urine. In this novel SPE, the formation of C₁₆mimBr with mixed hemimicelles on the surface of MCNTs@SiO₂ nanoparticles (NPs) causes retention of analytes by strong hydrophobic, π–π and electrostatic interactions. This SPE technique combines the advantages of mixed hemimicelles and MCNTs. In order to establish the guidelines for the preparation of mixed hemimicelles on composite materials, different main factors affecting the preconcentration of analytes, such as material type, amount of surfactant, pH of solution, ionic strength, extraction time, desorption condition and regeneration property, were investigated and optimized. Under the selected conditions, the accuracy of the method was evaluated by recovery measurements on spiked samples, and good recoveries with low relative standard deviations from 3.5% to 4.9% were achieved. No interferences were caused by endogenous compounds in human urine. For our knowledge, this is the first development of a mixed hemimicelles SPE based on MCNTs and IL for the extraction of trace analytes in complex biological samples.     

对羟基苯甲酸乙酯印迹聚合物固相微萃取制备及条件优化

采用分子印迹技术,以对羟基苯甲酸乙酯(模板分子):α-甲基丙烯酸(功能单体):乙二醇二甲基丙烯酸酯(交联剂)摩尔比为1∶4∶20,反应温度为80℃,反应时间为15h,本体聚合的方法合成印迹聚合物。利用微量进样器和玻璃毛细管自制分子印迹固相微萃取装置。将自制固相微萃取与气相色谱联用,并对萃取头的萃取条件如萃取温度、萃取时间、解析时间、溶液离子强度等进行优化。通过选择性吸附实验测得,分子印迹固相微萃取对对羟基苯甲酸甲酯、对羟基苯甲酸乙酯和对羟基苯甲酸丙酯的萃取量分别为103.54、134.26和114.68μg,均大于非分子印迹固相微萃取的萃取量47.88、49.24和41.41μg,印迹萃取头表现出了良好的吸附性和选择性。     

Morphology of oriented carbon fibers

Longitudinal microtome sections were obtained from two specimens of PAN-based commercial carbon fibers using three different cutting directions with respect to the fiber axis orientation. Evidence is presented that secondary features larger than the graphite fibril (i.e. 15–150 Å) seen in thin sections of these fibers were artifacts due to the interaction of the knife with the carbon fiber.     

微波萃取甘蓝叶绿素工艺研究

以甘蓝叶为原料。利用微波辐射萃取法提取甘蓝中的叶绿素。以辐射时间、破壁助剂、乙醇浓度、料液比、提取时间、提取温度等作为影响因素进行单因素试验,通过分析确定了单因素的最佳实验条件。采用正交实验设计,优化甘蓝叶绿素的提取条件。结果表明：微波萃取甘蓝叶绿素的最佳工艺条件为乙醇浓度95％,提取时间50min,提取温度60℃,料液比1：12。与传统提取方法相比较,叶绿素的提取率可提高20％左右。     

Quality of residual oil from palm-pressed mesocarp fiber (Elaeis guineensis) using supercritical CO2 with and without ethanol

The qualities of oils extracted from fresh and dried palm-pressed mesocarp fiber were evaluated. The means of extraction included conventional solvent extraction and supercritical carbon dioxide (SC-CO₂) extraction with and without addition of ethanol. Extraction efficiency using pure SC-CO₂ and the effect of moisture content on efficiency were studied. Minor components, such as vitamin F, carotenoids, squalene and phytosterols, obtained by different methods were compared. The quality of oil recovered from fresh palm-pressed fiber is generally better than that of oil recovered from dried fiber. The SC-CO₂ extraction rate was lower for fresh fiber than for dried fiber. The incorporation of ethanol with SC-CO₂ resulted in oil with higher oxidative stability than did SC-CO₂ alone. Concentrations of minor components and the acylglycerol compositions of the oils extracted from both types of fibers were similar.     

超声波提取法从花生红衣中分离白藜芦醇的条件优化

白藜芦醇是一种多酚类物质,具有非常重要的生理活性作用,研究发现在花生红衣中含有白藜芦醇。实验以花生红衣为原料,乙醇为提取剂,采用超声波技术提取花生红衣中的白藜芦醇。通过单因素试验,考察乙醇浓度、浸泡时间、提取时间、提取温度、萃取次数对白藜芦醇的提取效果的影响。结果表明,超声波法提取白藜芦醇的最佳条件为:乙醇浓度为80%,浸泡时间为4 h,超声波提取时间为40 min,提取温度为30℃,萃取次数为9次。最后通过紫外光谱和红外光谱检测得到的粗提取物中确实含有白藜芦醇。     

Fiber-reinforced cellulosic thermoplastic composites

Steam-exploded fibers from Yellow poplar (Liriodendron tulipifera) wood were assessed in terms of their thermal stability characteristics, their impact on torque during melt processing of a thermoplastic cellulose ester (plasticized CAB) matrix, their fiber–matrix adhesion and dispersion in composites, and their mechanical properties under tension. Fibers included water-extracted steam-exploded fibers (WEF), alkali extracted fibers (AEF), acetylated fibers (AAEF), and a commercial milled oat fiber sample (COF) (i.e., untreated control). The results indicate that the thermal stability of steam-exploded fibers increases progressively as the fibers are extracted with water and alkali and following acetylation. The greatest improvement resulted from the removal of water-soluble hemicelluloses. The modification by acetylation contributed to improved interfacial wetting that was revealed by increased torque during melt processing. Whereas modulus increased by between 0 and 100% with the incorporation of 40% fibers by weight, tensile strength either declined by ⅓ to ½ or it increased by a maximum of 10%, depending on fiber type. AAEF composites produced the best mechanical properties. Fiber–aspect ratio was reduced to an average of 25–50 from ≫ 200 during compounding. The superior reinforcing characteristics of AAEF fibers were also reflected by SEM, which revealed better fiber–matrix adhesion and failure by fiber fibrillation rather than by fiber pullout. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1329–1340, 1999     

Studies on fibers spun from poly(vinyl alcohol‐b‐acrylonitrile) emulsions prepared by ultrasonic technique. II. Properties of the fibers

The moisture content of poly(vinyl alcohol‐b‐acrylonitrile) fibers decreases with an increasing hydrophobic AN content and crystallinity of the fibers; however, the copolymer fiber with 26.94% AN, drawn × 5, and heat‐treated at 200°C has a moisture content value slightly lower than that of commercial PVA fiber, but much higher than that of commercial PAN fiber. The block copolymer fibers have a water‐retention value higher than that of commercial PVA fiber, owing to the presence of voids in these fibers, and have a stronger wicking ability than that of commercial PVA, PAN fibers, and wool and cotton mainly due to the grooved surface and bulk porous morphology of the fibers. The tensile strength of the copolymer fibers with an appropriate AN content are lower than that of commercial PVA fiber, but higher than that of commercial PAN fiber and much higher than that of wool and cotton. The melting temperatures of the copolymer fibers increase with increasing heat‐treatment temperature. The copolymer fibers possess a lower peak cyclizing temperature than that of the PAN fiber and have a higher thermal stability than that of both PVA and PAN fibers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 989–994, 2001