浊点萃取在金属离子分析中的应用

通过表面活性剂浊点特性实现胶束相分离以达到样品预富集,是一种新兴的液 -液萃取方法。该方法广泛应用于痕量有机物、金属离子(通过形成螯合物)以及生物大 分子的提取,具有低毒、高效、安全、简便等特点,其富集率最高可达100％。     

单滴微萃取的应用进展

单滴微萃取(single-drop microextraction,SDME)是近年发展起来的一种新型环保分离富集技术,引起人们的广泛兴趣。与常规液液萃取相比,它有诸多的优点:有机萃取溶剂用量非常小,不造成二次污染;有机萃取相与水相的相比小,富集倍数大;萃取效率高;每次萃取使用新的有机萃取剂微滴,重现性好;应用范围广,可用于有机物、痕量金属元素和金属有机化合物的预富集;样品萃取液可直接进样检测,便于与其他分析仪器实现联用;样品和试剂消耗小;操作简便、快捷等。单滴微萃取是分离和富集痕量金属离子。有机化合物的有效方法,是一种有发展前途的的分离富集技术。     

原子吸收光谱分析中的绿色萃取富集技术

分析复杂样品和测定痕量组分时,样品预处理是获得准确结果的必要条件。萃取是广泛使用的分离富集方法,近年来,分析工作者陆续开发了多种新型绿色微萃取技术,包括单滴微萃取、浊点萃取、分散液-液微萃取、室温离子液体萃取、固-液萃取、固相微萃取、分子印迹聚合物萃取等。他们共同的优点是：有机萃取溶剂用量非常小;萃取效率高,富集倍数大;样品和试剂消耗少;操作简便、快速;便于与其他分析仪器联用;应用范围广等。本文介绍这些新型绿色萃取技术近3年来的进展,引用文献85篇。     

浊点萃取-原子吸收光谱法测定生物试样中微量锰

研究了浊点萃取(CPE)-火焰原子吸收光谱法(FAAS)测定微量锰的新方法.利用表面活性剂聚乙二醇辛基苯基醚(Triton X-100)和络合剂2[(5-溴-2-吡啶)-偶氮]-5-(二乙氨基)苯酚(5Br-PADAP)对试样中的锰(Ⅱ)进行浊点萃取.详细探讨了影响浊点萃取及测定灵敏度的因素.在最佳条件下,锰的富集倍率为10,检出限为4.18 ng/mL(n=11),RSD为2.3%(CMn2 =0.20 μg/mL,n=5),锰含量在0.010～0.50 μg/mL范围内服从比尔定律.用该方法对经微波消解黄豆试样中的锰进行富集和测定,结果令人满意.     

一种新的液液萃取模式-分散液液微萃取

分散液-液微萃取是2006年才问世的一种新型微萃取技术。它基于使用微量注射器将微升级萃取剂快速注入样液内,在分散剂-水相内形成萃取剂微珠,很大地扩展了有机萃取剂和水样之间相接触面,大大加快了萃取平衡的速度,使目标化合物迅速萃入萃取剂微珠内,提高了萃取效率和富集倍数。萃取富集操作与后续检测方法有很好的相容性,萃取相可直接进样气相色谱、高效液相色谱、薄层色谱、气相色谱-质谱、分光光度、火焰原子吸收光谱和电热原子吸收光谱,对目标化合物进行测定。它不仅适用于痕量有机物的分离富集,也适用于痕量无机金属离子的分离富集,已成功地应用于各种坏境水样(包括高含盐量水样)、多种饮料、生物样品、煤和矿物样品中痕量组分的分离富集,是一种有发展前途的环境友好的分离富集技术。     

毛细管电泳分析中的样品预富集新技术

本文综述了pH调制样品堆积、浊点萃取、固相萃取三种用于毛细管电泳分析 中的样品预富集新技术的原理、特点。     

单滴微萃取的应用进展

单滴微萃取(single-drop microextraction,SDME)是近年发展起来的一种新型环保分离富集技术,引起人们的广泛兴趣。与常规液液萃取相比,它有诸多的优点:有机萃取溶剂用量非常小,不造成二次污染;有机萃取相与水相的相比小,富集倍数大;萃取效率高;每次萃取使用新的有机萃取剂微滴,重现性好;应用范围广,可用于有机物、痕量金属元素和金属有机化合物的预富集;样品萃取液可直接进样检测,便于与其他分析仪器实现联用;样品和试剂消耗小;操作简便、快捷等。单滴微萃取是分离和富集痕量金属离子。有机化合物的有效方法,是一种有发展前途的的分离富集技术。     

浊点萃取-紫外光谱法分离分析苯酚

本文将浊点萃取技术与紫外光谱法联用，用于苯酚的分离分析，优化了Triton X-100用量、加热时间和pH等萃取条件。对环境水样中的苯酚进行测定，结果令人满意。     

液—液连续萃取仪

介绍了一种全玻璃结构的液－液连续萃取仪。仪器采用以循环系统，即可用于比水重的萃取溶剂，又可用于比水轻的萃取溶剂。水样流速５－１０Ｌ／ｈ，回收率６０％－８０％。富集倍数达１０＾４倍，适于富集大量水中的低浓度污染物。     

超临界流体萃取实验技术

超临界流体萃取是一种高效率选择性样品分离技术，已被广泛应用在工业生产，环境检测和分析化学等领域，对超临界流体萃取仪器流程及实验技术作了简要综述，着重讨论了影响超临界流体萃取的因素和实验条件。     

Behaviour of polynuclear aryl sulphonates

A series of hexadecyl polynuclear aromatic, decalin, and tetralin sulphonates have been synthesised. The critical micelle concentration (CMC) and surface and interfacial tension values at various concentrations above and below the CMC in both aqueous and non‐aqueous media have been determined. The micellar size and shape, the average number of monomers constituting these micelles, and the thermodynamic properties have also been estimated. These studies show that the CMC value in both aqueous and heptane media decreases with an increase in the number of aromatic rings in the sulphonates. The size and shape of the micelles do not change appreciably in heptane, although the number of monomers constituting the micelles changes with a change of structure of the aromatic moiety. The thermodynamic parameters do not seem to affect the surface activity and solubilising properties even though the free energy, enthalpy, and entropy decrease with an increase in the size of the aromatic moiety. The surface and interfacial tension values are the lowest with aqueous and non‐aqueous solutions of hexadecyl naphthalene sulphonate, but these values increase with an increase in the number of aromatic rings in the sulphonates. The sizes of the micelles of hexadecyl naphthalene sulphonate in aqueous solutions and the number of monomer molecules constituting the micelles are greater than for the other aromatic sulphonates. Although the sizes of micelles of hexadecyl benzanthracene sulphonate and hexadecyl pentacene sulphonate are comparable, the numbers of molecules constituting these micelles are the smallest. The solubilisation of alkanes in aqueous solutions of sodium naphthalene sulphonate containing electrolyte and isobutanol is the highest, but it falls off rapidly for all the other sulphonates. This shows the extreme sensitivity of solubilisation to the structure of the sulphonates. The detergency increases with an increase in the size of the aromatic moiety. The structure thus has a profound influence on the surface and micellar properties of these sulphonates. These studies are important from the point of view of the use of synthetic sulphonates as additives / surfactants in place of petroleum sulphonates.     

新型萃取技术-原子吸收光谱在食品内重金属分析中的应用

食品安全是人们普遍十分关心的问题,发展新的食品检测技术有关于民生的大事,具有十分的重要的意义。食品分析涉及营养成分、添加剂、有毒有害的有机农药残留和无机重金属杂质检测等多个方面。本文仅介绍了新型绿色萃取技术结合原子吸收光谱在食品中有毒有害重金属组分检测中的应用,绿色萃取技术包括固相萃取(SPE)、单滴微萃取(SDME)、分散液-液微萃取(DLLME)、浊点萃取(CPE等),以及室温离子液体(RTIL)、分子印迹聚合物(MIP)在萃取中的应用。引用文献50篇。     

DETERMINATION OF COPPER(II) IN NATURAL WATERS BY EXTRACTION USING N-O-VANILLIDINE-2-AMINO-P-CRESOL AND FLAME ATOMIC ABSORPTION SPECTROMETRY

A simple and accurate solvent extraction method was developed for the separation and preconcentration of trace levels of copper(II) in water using N-o-vanillidine-2-amino-p-cresol prior to its determination using flame atomic absorption spectrometry. Analytical parameters such as the pH of the aqueous phase, extraction time, concentration of the reagent, concentration of the nitric acid back extraction agent, volumes of aqueous phase and back extraction agent, and concomitant ions on the extraction yield of the copper(II) were investigated and optimized. Under the optimal conditions, the detection limit (3σ) was 0.61 µ g L^?1 for a 25 mL blank solution, yielding a preconcentration factor of 12.5. The method was succesfully applied to the determination of copper(II) in tap water, river water, and seawater. The accuracy of the method was verified by analyzing two certified reference materials and spiked water samples. The results obtained were in agreement with the certified values and the recoveries for spiked water samples were between 98 and 112%.     

Modified nanoporous carbon as a novel sorbent before solvent-based de-emulsification dispersive liquid–liquid microextraction for ultra-trace detection of cadmium by flame atomic absorption spectrophotometry

Combination of different extraction methods is an interesting work in the field of sample pretreatment. In the current study, for the first time, solid phase extraction combined with solvent-based de-emulsification dispersive liquid–liquid microextraction (SPE-SD-DLLME) was developed for preconcentration and trace detection of cadmium in water samples using flame atomic absorption spectrophotometry (FAAS). The adsorbed cadmium ions on prepared SPE (75 mL of aqueous solution) were eluted by optimized elution solvent and introduced to the second microextraction step. The effective variables of SPE including the pH of sample, flow rates, type, concentration and volume of the eluent and the effect of potentially interfering ions of the separation of cadmium were evaluated and optimized. Also, several factors that influence the SD-DLLME step such as pH, neocuproine concentration (the cadmium binding ligand), type of dispersed/de-emulsifier solvent, volume of disperser/de-emulsifier solvent and type and volume of extraction solvents were investigated. SPE-SD-DLLME provides a preconcentration factor of 165 for cadmium ions. Calibration plot was linear in the range of 0.1–50 μg L⁻¹ with correlation of determination (r²) of 0.988. The precision and limit of detection of proposed method were 5.1% (RSD%, n = 8) and 0.03 μg L⁻¹, respectively.     

The Effect of Concentration on Lubricating Properties of Aqueous Solutions of Sodium Lauryl Sulfate and Ethoxylated Sodium Lauryl Sulfate

The objective of this study was to formulate new ecological lubricating substances, primarily water-based, and to verify their tribological and physicochemical properties. Initially, simple binary solutions were investigated. Then, various additives were added depending on application targets. Two alkyl sulfates were selected as additives modifying lubricating properties of water: sodium lauryl sulfate (SLS) and ethoxylated sodium lauryl sulfate (ESLS). They have an identical hydrophobic part in the form of an alkyl chain consisting of 12 carbon atoms. The SO₄ ²⁻ anion forms the hydrophilic part in SLS molecules, whereas an ESLS molecule also contains two mers of ethylene oxide which cause an increase in its hydrophilicity relative to SLS. Both SLS and ESLS exhibit high surface activity measured by their surface tension. Micelles form in aqueous solutions of alkyl sulfates at low concentrations of the order of 1%, whereas the presence of liquid crystalline phases can be found at the concentrations of 40 and 70%. High surface activity and formation of structures in the solutions (micelles, mesophases) formed the basis for application of the compounds as additives modifying lubricating properties. Tribological properties of aqueous solutions of alkyl sulfates were verified with a four-ball machine (T02 tester) at a constant load of 2 kN. The values of friction coefficient (μ) were a measure of motion resistance, while the wear scar diameter (d) was a measure of wear. Alkyl sulfates significantly improve tribological properties of water. The coefficient of friction decreased sixfold and the wear scar diameter decreased by as much as twofold relative to the base. Non-monotonic changes in the tribological properties measured were observed as a function of concentration of additives. An attempt was made to relate those atypical changes with the presence of micelles and mesophases in both the surface phase and the bulk phase. In the model proposed the whole concentration range was divided into four areas in which tribological properties correspond well with physicochemical properties, particularly with the structures formed in solutions and at the interface.