连续逆流提取机及其在绞股蓝皂苷提取工艺中的应用

简述了中草药连续逆流提取机的基本结构和工作原理.以水为溶媒、绞股蓝为原料,进行绞股蓝有效成分的提取试验.以绞股蓝水溶出物和总皂苷为目标物,考察提取温度、液料比和提取时间等因素对提取得率的影响,并通过L9(33)正交实验设计,对提取工艺进行优选.采用中草药连续逆流提取机提取绞股蓝有效成分的最佳工艺条件:提取溶剂温度80 ℃,料液比1:35(g/mL),提取时间50 min;所得提取物得率为33.95%,总皂苷得率为8.9%.     

Effect of salts on the extraction characteristics of succinic acid by predispersed solvent extraction

Predispersed solvent extraction (PDSE) of succinic acid with Tri-n-octylamine (TOA) dissolved in 1-octanol from aqueous solutions of 50 g/L succinic acid was examined. It was found that the equilibrium data in PDSE was equal to that in conventional solvent extraction in spite of the lack of mechanical mixing in PDSE. The influence of salts on succinic acid extraction and the stability of colloidal liquid aphrons (CLAs) were also investigated. Results indicated that in the presence of sodium chloride, less succinic acid was extracted by CLAs and the stability of CLAs decreased. However, the stability of CLAs was sufficient to make PDSE practically applicable to real fermentation broth, considering the concentration range of salts in the fermentation process for succinic acid.     

超声波辅助抽提法在孔雀石绿分子印迹固相萃取中的应用

采用沉淀聚合法制备孔雀石绿分子印迹聚合物(MG-MIPs),以洗脱效率及吸附量为指标,考察超声波辅助抽提法对MIPs中MG洗脱效果及吸附性能的影响,通过扫描电镜观察MIPs的表面形态,并对其吸附性能进行研究。结果表明:模板分子MG在超声30 min、超声10次、料液比m(MG-MIPs)∶V(甲醇-乙酸溶液)为1∶10(g/m L)、温度为25℃、超声功率为270 W的条件下,洗脱效果最好,MIPs在固相萃取柱中的吸附效率较高,达到198μg/g。     

番茄红素提取工艺的优化

通过研究预处理方法、有机溶剂及混合溶剂、温度、时间和固液比等因素对分离番茄红素的影响,探索最优化工艺,为工业化高效提取提供依据.实验结果表明:优化温度55℃,温浴番茄果皮浆状物2.5 h后,经离心、乙醇洗涤,再按照固液比为1:4(g/mL),用V(石油醚):V(丙酮)为1:2的混合溶剂在封口容器中,于50℃水浴中萃取番茄红素25 min,期间不断轻微摇晃以确保萃取充分.用此法提取番茄红素成本低、效率高、易于自动化,具有广阔的工业化应用前景.     

Recent extraction techniques for natural products: microwave-assisted extraction and pressurised solvent extraction

In the last 10 years there has been an increased interest in using techniques involving microwave-assisted extraction and pressurised solvent extraction in analytical laboratories. This review gives a brief overview of both methods, and reports on their application to the extraction of natural products. The influence of parameters such as the nature of the solvent and volume, temperature, time and particle size of the matrix is discussed. Through numerous examples, it is demonstrated that both techniques allow reduced solvent consumption and shorter extraction times, while the extraction yields of the analytes are equivalent to or even higher than those obtained with conventional methods.     

Response surface methodology for the extraction of wedelolactone from Eclipta alba using aqueous two-phase extraction

Abstract

Aqueous two-phase extraction of wedelolactone from Eclipta alba was studied using the polymer-salt system. The system consisted of polyethylene glycol (PEG) as a top phase (polymer) and sodium citrate as a bottom phase (salt). Process parameters such as PEG concentration, PEG molecular weight, salt concentration, and pH have been optimized using response surface methodology (RSM) with the help of central composite design (CCD). The optimized conditions for aqueous two-phase system (ATPS), in the case of one factor at a time approach, were found as PEG 6000, PEG concentration 18% (w/v), salt concentration 16% (w/v), and pH 7; with maximum extraction yield of 6.52?mg/g. While, RSM studies showed maximum extraction yield of 6.73?mg/g with the optimized parameters as PEG 6000, PEG concentration 18% (w/v), salt concentration 17.96% (w/v), and pH 7. ATPS was found to give a 1.3 fold increase in the extraction yield of wedelolactone as compared to other conventional extraction methods.     

Pectin extraction in the presence of alcohols

A theoretical discussion of the extraction process and especially of the factors influencing extractant penetration in pectin-containing raw materials is presented. The necessity of adding surfactant in the pectin extraction is proved. Experiments were carried out with two types of apple pressings differing in anhydrouronic acid content and quantity of extractable pectin.

The addition of low molecular alcohols in concentrations from 1% to 3% to the acid extragent resulted in an acceleration of extraction and increase in the pectin yield by 55–90%. Ethylene glycol, glycerol and diethylene glycol had a better effect than monohydric alcohols. The effect of the process duration on the pectin yield during acid extraction was studied. A 25-min extraction was sufficient for taking out the extractable pectin. It was shown that the addition of alcohols resulted in a measurable increase in the pectin gel strength.     

Studies on the extraction and back-extraction of a recombinant cutinase in a reversed micellar extraction process

This work deals with the extraction and back-extraction of a recombinant cutinase using AOT reversed micelles in isooctane. The effect of pH, ionic strength, AOT concentration and temperature on the extraction and back-extraction of the cutinase was investigated. High extraction (97%) of the cutinase was achieved at pH 7.0 with a 50 mM Tris-HCl buffer solution containing 100 mM KCl, but a low activity was detected in the reversed micellar phase. At pH 9.0, cutinase was extracted (75%) to the reversed micelles with higher activity. Cutinase was recovered (50%) from a reversed micellar phase (100 mM AOT/isooctane) into a 50 mM Tris-HCl buffered solution at pH 9.0 with 100 mM KCl, and 20°C. Protein and cutinase activity global yields of 38 and 45%, respectively, were obtained for the global process, extraction and back-extraction steps, using low ionic strength, pH 9.0, 100 mM AOT and 20°C.Maria das Graças Carneiro da Cunha acknowledges a Ph.D. fellowship from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Centro de Pesquisas Aggeu Magalhães, Brasil. This work was partly financed by the BRIDGE Programme (Contract BIOT-CT91-0274(DTEE)).     

On the extraction and alignment of image edges

In this paper the types of image filtering, segmentation and correlational processes which are consistent with the ability of human observers to align edges in arbitrary two-dimensional images are considered. Edge-only versions of a number of images were computed by pre-filtering, segmenting and using laplacians to extract luminance boundaries. The matching of such edge-only images with the originals seems well predicted by a (derivative) matched filtering (cross-correlation) process showing some bias toward edges contained within the middle frequency range of the images used.     

Stereology in the extraction of information from images

Some important aspects for information extraction by stereology from images in surgical and experimental pathology are discussed. The relationship between stereology and morphometry is briefly discussed, with the most important conditions for stereologic analysis in pathology pointed out. The possibilities, limits and problems inherent in stereologic and morphometric analysis in pathology are explained in two examples: so-called "small airways disease" and tight junctions of hepatocytes during physiologic choleresis.     

Optimization of neuropeptide extraction from the mouse hypothalamus

Sample preparation for neuropeptidomic studies is a critical issue since protein degradation can produce high levels of peptides that obscure the endogenous neuropeptides. We compared different extraction conditions for the recovery of neuropeptides and the formation of protein breakdown fragments from mouse hypothalami. Sonication and heating in water (70 degrees C for 20 min) followed by cold acid and centrifugation enabled the efficient extraction of many neuropeptides without the formation of protein degradation fragments seen with hot acid extractions. The hot water/cold acid extraction procedure resulted in the reproducible recovery of many hypothalamic peptides, including several novel peptides.     

An improved method for the extraction of prostaglandins

Present methods of extracting prostagalndins (PGs) give poor recoveries from synovial fluid, probably because the PGs bind to protein and are lost in the precipitation stage of extraction. Addition of the nonpolar detergent sodium lauryl sulphate prior to extraction improves recovery of PGs. It is suggested that sodium lauryl sulphate competes with PGs for the binding sites.