An improved separation of aflatoxins

Crude aflatoxin from a chloroform extract ofAspergillus flavus cultures on rice was precipitated with Skelly Solve B and chromatographed on 100–200 mesh silica gel columns, using ethyl acetate as eluant. On this column there was no separation of aflatoxins from each other, but most of the brown, oily material was removed. The next step in the purification was chromatography on 100–200 mesh silica gel columns with chloroform and 5% methanol/chloroform as eluants. A large part of the B₁ was purified, but B₂, G₁ and G₂ did not separate, and M₁ had a brown oil that prevented crystallization. The M₁ was purified by chromatography on Sephadex LH-20 with chloroform; the brown material was retained while the M₁ passed through. The separation of aflatoxin B₂, G₁, and G₂ was achieved by column chromatography on Silica Gel H for TLC. In addition, aspertoxin was separated and identified. The purity and identity of the compounds were established by 100 MHz NMR. Presented at the AOCS-AACC Joint Meeting, 1968, Washington, D.C. W. Utiliz. Res. Dev. Div., ARS, USDA.     

A low-energy solvent separation method

This paper presents a new low-energy method to separate solvents from polymers. The method is based upon the lower critical solution temperature (LCST), a phenomenon exhibited by all nonpolar polymer-solvent systems. Three key issues concerning this new separation method are discussed for the specific system of high cis polybutadiene in a commercial grade n-hexane. The first issue, energy cost, is greatly reduced from present commercial separation processes by avoiding the liquid-vapor phase transition for more than half of the solvent. The predicted energy cost for the new method (not including inefficiencies) is about 15 percent of the present energy cost (including inefficiencies). The second issue, recycling of the dilute phase with terminator, is shown not to be a serious problem, and a solution is suggested based upon available methods. The third issue discussed, and perhaps the most difficult, is the physical separation of the two phases. This is solved by inducing spinodal decomposition, which leads to rapid gravity separation. Several alternative separation scenarios based upon this idea are presented at the end of the article.     

A new solvent for cellulose

A new solvent for cellulose was prepared by dissolving copper (II) hydroxide in an aqueous solution of 1,3-diaminopropane. The solvent displays an efficiency equal to cuprammonium and superior to other previously reported metal complex solvents; a mechanism for the dissolution has been proposed. Solutions of cellulose in the new solvent were used to prepare thin cellulose membranes.     

Application of TLC chemical confirmatory tests to minicolumn chromatography of aflatoxins

The minicolumn (MC) proposed by Holaday and Lansden was developed with standard aflatoxin solution and also with the extracts of corn, rice, wheat, cottonseed, peanut cake and black pepper; each having different levels of aflatoxins. One-half mL each of 2,4-dinitrophenylhydrazine,p-anisaldehyde, 20% H₂SO₄, 20% HCl and trifluoroacetic acid (TFA) with 25% HNO₃, which were used for confirming aflatoxins on TLC, were applied to the developed column. Among these, all the 3 acid reagents changed the blue fluorescence of aflatoxins to yellow and thus were found to be satisfactory confirmatory tests. The TFA with 25% HNO₃ had the lowest detection limit-5 ppb.     

聚酰亚胺膜的制备及对有机物系的纳滤分离

针对以均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为原料合成聚酰亚胺的过程,研究了亚胺化方法、凝胶浴组成与温度等条件对膜的结构和分离性能的影响。实验结果表明,当聚酰胺酸铸膜液质量分数为15%、凝胶浴为30%乙醇(质量)的醇水溶液时,所制得的聚酰亚胺纳滤膜具有最佳的分离性能。操作压力为2MPa下稳态操作时,该膜对酮苯脱蜡工艺后的溶剂与润滑油基础油混合物的截留率达66%,通量为4.26L/(m2.h),为有机溶剂体系的纳滤膜分离技术的工业应用提供了基础。     

低共熔溶剂用于萃取分离的研究进展

作为一种新型的绿色溶剂,低共熔溶剂（DES）拥有与离子液体媲美的优良特性,如挥发性小、可设计性等,且具有成本低廉和制备简单的优势,使得DES正逐步替代传统有机溶剂,在萃取分离应用方面得到广泛的关注。本文综述了近年来国内外有关DES在萃取分离方面的研究报道,阐述了DES直接用于液液萃取、在线生成DES的缔合萃取和通过DES分解完成萃取的应用,并分析比较了各过程的特点和存在的问题;介绍了DES在不同萃取体系中的稳定性和DES的回收方法;总结了DES萃取分离体系的理论发展和萃取机理的研究进展;展望了DES用于萃取分离的工业化前景,指出了目前面临的DES理论、萃取机理、循环稳定性等方面的挑战,分析了进一步的研究趋势。     

The rapid separation of aflatoxins on silica gel coated glass cylinders

A chromatographic method is described for the separation of aflatoxins on silica gel coated glass cylinders prepared with a chloroformacetone slurry. This can be done in 35–40 min compared with more than 2 hr for thin layer chromatography (TLC). This method is more rapid, economical and its sensitivity is comparable to TLC. University of Georgia College of Agriculture Experiment Stations, Journal Series Paper Number 643, College Station, Athens, Ga.     

Silica-based solvent impregnated adsorbents for separation of rare earth metals

Silica-based solvent impregnated adsorbents are prepared, employing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester as an extractant. Two kinds of silica particles are used as supports; (i) those whose surface is coated by a styrene/divinylbenzene copolymer and (ii) those whose hydroxyl-terminated pentadimethyl siloxane group is immobilized on the surface. The adsorbent based on silica particles coated by styrene/divinylbenzene can be repeatedly used for adsorption–elution processing, while the adsorption capacity of the adsorbent based on silica particles modified by the siloxane group is decreased by repeated cycles. The adsorbent is applicable to chromatographic operation for Dy/Nd, and quantitative adsorption–elution is achieved.     

表面活性剂强化重质油矿溶剂萃取残渣中残留溶剂鼓泡分离

针对重质油矿溶剂萃取残渣中残留溶剂的回收和去除问题,本文在鼓泡分离工艺的基础上提出了表面活性剂强化鼓泡分离工艺,探究了表面活性剂种类对于鼓泡分离过程的影响,并研究了阴离子表面活性剂十二烷基硫酸钠（SDS）对于鼓泡分离过程的动力学。结果表明,表面活性剂种类对去除效果具有重要影响：SDS可以通过降低甲苯-水界面张力和增加固体表面的亲水性,促进甲苯液层从固体颗粒表面的脱离,进而强化鼓泡分离过程,该过程符合一级动力学模型。然而,阳离子表面活性剂十四烷基三甲基溴化铵（C₁₄TAB）和双亲性表面活性剂月桂基甜菜碱（SB-12）则通过增加固体表面的疏水性,促使颗粒离开溶液体系,抑制了鼓泡分离的进行,但由于SB-12对固体表面改性的程度弱于C₁₄TAB,SB-12的抑制作用弱于C₁₄TAB,且随鼓泡时间的延长,SB-12对甲苯-水界面张力的改变成为影响鼓泡分离效果的主要因素,SB-12对鼓泡分离过程的影响由抑制转为强化,但C₁₄TAB在鼓泡分离过程中始终呈现抑制作用。上述结果对于类似的固相溶剂萃取后残留溶剂去除或回收具有一定的理论指导意义。     

桑葚果渣花色苷的低共熔溶剂提取与分离

以桑葚果渣为原料,在低共熔溶剂(DESs)中,经DESs提取与大孔树脂分离两步,回收了果渣中花色苷.测试了不同类型DESs与提取方法对花色苷提取率的影响,通过不同型号大孔树脂作为吸附载体对花色苷进行回收以脱除DESs.采用HPLC、HPLC-MS对花色苷进行定量与定性分析.结果表明,DESs中草酸-氯化胆碱〔n(草酸)...     

一种含尘煤焦油分离的新方法

介绍了鲁奇炉煤加压气化过程中所产生的含尘煤焦油(通常作为废渣烧掉)的处理,采用一种新的三相卧螺离心分离方法,将其进一步分离为煤焦油、尘和水,有效解决了多年来棘手的煤焦油工业废渣问题。该方法具有操作性强,经济效益、社会效益高的特点。     

溶剂萃取法净化湿法磷酸新工艺

对贵州瓮福磷矿所制湿法磷酸进行了溶剂萃取的中间试验,考察中试设备及材质的适应性,对以磷酸三丁酯作萃取剂净化湿法磷酸的工艺流程和相关技术进行了研究,完成了3000t/aP2O5湿法磷酸净化中试试验。     

A system for determining optical brighteners in laundry detergents by TLC and HPLC

Twenty-three optical brighteners have been separated on a thin-layer chromatographic (TLC) system and a high-performance liquid chromatographic (HPLC) system. These systems can be used to identify and quantitate optical brighteners in laundry detergents. The TLC system uses four solvent-absorbent combinations. The HPLC system uses a C₈ column and a binary solvent gradient program to separate the optical brighteners.     

计算机辅助筛选分离联苯与4-联苯乙酮两种化合物的溶剂

引言4-联苯乙酮是合成非甾体抗炎药联苯乙酸和液晶材料的重要精细化工中间体[1].以联苯为原料,在无水三氯化铝存在下,用乙酰氯或醋酐进行傅一克反应可合成4-联苯乙酮[2-3];反应结束后加入碎冰和盐酸水解,然后静置分层,分出油层,水层用二氯乙烷多次萃取;萃取物并入油层,减压蒸去溶剂后可得到4-联苯乙酮粗品;文献[4]以氯仿为萃取剂从水层中提取目的产物.     

低共熔溶剂预处理杨木水解渣拆解木质素

为高效去除木质纤维素中的木质素,获得富含纤维素的底物,实现木质纤维素组分的单一分离与组分全利用,制备合成了6种三元低共熔溶剂(deep eutectic solvent, DES),利用DES预处理已去除半纤维素的杨木水解渣,研究了6种低共熔溶剂对木质素去除和纤维素保留的影响,并优化获得了最佳的预处理工艺参数。结果表明,6种DES中苄基三乙基氯化铵-乙二醇-氯化铁(T-EG-Fe)的预处理效果最优,木质素去除率为80.46%,纤维素保留率为90.81%。优化得到T-EG-Fe预处理杨木水解渣最佳工艺条件为:反应固液比为1∶15,反应温度为130℃,反应时间为5h,在最优条件下预处理得到的固体残渣中纤维素质量分数为92.78%,木质素质量分数为5.33%。T-EG-Fe具有高效拆解木质素的潜力,在木质纤维素预处理过程中具有一定的应用价值。     

非有机溶剂液/固萃取分离在分析化学中的应用进展

非有机溶剂液-固萃取分离体系是近十几年发展起来的一种新型高效分离技术,它有两种萃取体系:1)聚合物-盐-水液-固体系;2)盐-三元缔合物-水液-固体系.由于此分离技术具备分离设备简单、速度快、收率高、不使用有毒有机溶剂等特点,受到研究人员的高度关注,目前已经广泛应用到金属离子分离和生物活性物质纯化过程中.重点阐述了该体系的基本原理、影响分离效率的有关因素及研究进展,并对下一步发展进行了展望.     

Feasibility of 1,3-butanediol as solvent for limonene and linalool separation

Liquid–liquid equilibrium of the system limonene + linalool + 1,3-butanediol has been studied at two different temperatures. The obtained data were satisfactorily correlated with the NRTL activity coefficient model, in order to obtain the binary interaction parameters of the mixture. Later on, an extraction column was simulated with ASPEN PLUS^® software, to ascertain the feasibility of 1,3-butanediol as solvent for limonene and linalool separation and to determine the advantages of this solvent over the employed previous ones in this process. The influence of the number of theoretical stages and the solvent/feed ratio over the amount and purity of the recovered limonene and linalool were also studied.     

A rapid screening method for the aflatoxins and ochratoxin A

A rapid, economical minicolumn procedure for screening aflatoxins and ochratoxin A in a wide range of products is presented. The technique includes high speed blending of the sample with aqueous methanol, purification of the extract with a solution of zinc sulfate and phosphotungstic acid, partitioning in benzene, and minicolumn chromatography. Sensitivities of 4 ppb for the aflatoxins and 20 ppb for ochratoxin A could be achieved; and the simplicity of the method, which includes the use of disposable plastic and glass items, makes the method practical for field or in-plant applications.