液/液界面萃取循环伏安法测定Pb2+离子研究

本文利用吡咯烷二硫代氨基甲酸铵（APDC）作为螯合剂,甲基异丁酮（MIBK）作为萃取剂,将水相中的Pb2+萃取到有机相中,利用经典的三电极系统研究该有机相在液/液界面的伏安特性。实验结果表明,该电化学过程是一个由扩散控制的不可逆过程,Pb2+的萃取物从有机相转移到水相。铅萃取物的转移峰在0.16V vs.SCE处,并且在1.0×10-5~ 9.0×10-5mol/L范围内与峰电流大小成正比。这一方法为工业废水中铅的在线、现场测定提供了可靠、灵敏的监测方法。     

甲基异丁酮碘萃合物-水界面上的循环伏安法间接测定水溶液中氧化性金属离子

利用甲基异丁酮(MIBK)作为萃取剂,等体积法将水中的碘萃取到有机相中,微量进样器将20～40μL有机溶液注入玻璃微管中,使它处于界面上。利用经典的三电极系统研究该有机相在液/液界面的伏安特性。实验结果表明,该过程是一个受扩散控制的不可逆过程。有机相中碘的含量和峰电流大小在一定范围内成正比。利用这一特性可以间接测定水溶液中具有氧化性的金属离子(如Cr2O72-、Cu2 等)的含量,检出限为10-5mol/L。     

Pb2＋在液/液界面迁移的电化学研究及其应用

用循环伏安法研究了双硫腙络合推动Pb^2＋在水/乙酰丙酮界面迁移的伏安过程. 实验证明, 该过程是受扩散控制的不可逆过程, Pb^2＋由水相转移到有机相中, 与双硫腙形成络合物Pb(DzH)₂. Pb^2＋的峰电位在－0.3 V处, 并且在5× 10^－6～0.1 mol•L^－1范围内与峰电流成正比. 这一方法为工业废水中铅的在线、现场测定提供了可靠、灵敏的检测方法.     

Pb2＋在液/液界面迁移的电化学研究及其应用

用循环伏安法研究了双硫腙络合推动Pb^2＋在水/乙酰丙酮界面迁移的伏安过程. 实验证明, 该过程是受扩散控制的不可逆过程, Pb^2＋由水相转移到有机相中, 与双硫腙形成络合物Pb(DzH)₂. Pb^2＋的峰电位在－0.3 V处, 并且在5× 10^－6～0.1 mol•L^－1范围内与峰电流成正比. 这一方法为工业废水中铅的在线、现场测定提供了可靠、灵敏的检测方法.     

分散固相萃取-分散液液微萃取/高效液相色谱法测定西瓜中氟唑菌酰羟胺残留

采用分散固相萃取和分散液液微萃取联用的方法,建立了高效液相色谱快速检测西瓜中氟唑菌酰羟胺残留的分析方法。使用乙腈和水混合溶液作为萃取溶剂,经N-丙基-乙二胺硅烷(PSA)固相萃取吸附剂净化提取液,分散液液微萃取将目标物富集到1,1,2,2-四氯乙烷溶剂中,采用高效液相色谱进行分析。考察了萃取溶剂的种类与体积、分散剂体积及盐浓度等因素对分散液液微萃取萃取效率的影响。结果表明:分析物的质量浓度在0.01~5 mg/L范围内与峰面积的线性关系良好,相关系数(r)为0.999 9,定量下限(S/N=10)为0.01 mg/kg。加标水平为0.01、0.1、1 mg/kg时,平均回收率为89.2%~94.5%,相对标准偏差(n=5)为3.0%~8.7%。该方法简单、高效、灵敏度高,适用于西瓜中氟唑菌酰羟胺的残留检测。     

水中酚类化合物的液-液-液微萃取/ 高效液相色谱联用分析研究

建立了液-液-液微萃取/高效液相色谱联用(LLLME/HPLC)测定环境水中痕量酚类化合物2-甲基苯酚、2-硝基苯酚、2,4-二氯苯酚的分析方法,研究了有机相溶剂种类及其体积、料液相pH值与离子强度、接受相的体积、组成及浓度和搅拌速率、萃取时间等因素对分析物萃取效率的影响。实验结果表明,该方法对酚类化合物的富集倍数可达到404~747倍,方法的线性范围为0.2~300μg/L,RSD(n=6)为6.8%~11.4%。测定加标自来水、江水以及生活污水样品的回收率为83%~110%。     

膜修饰液/液界面上亚叶酸离子的转移

采用复合介孔膜修饰水/1,6-二氯己烷(W/DCH)界面得到阵列介观W/DCH界面,利用循环伏安法、差分脉冲伏安法以及计时电量法考察了亚叶酸离子在该阵列介观W/DCH界面上的转移过程.结果表明,亚叶酸离子在膜修饰W/DCH界面上转移的电化学响应与复合介孔膜内表面活性剂十六烷基三甲基溴化铵密切相关.循环伏安结果表明,亚叶酸离子由膜内水相向油相转移的峰电流与扫描速率的平方根呈线性关系,根据Randles-Sevik方程,计算得到亚叶酸离子在复合介孔膜内水相中的扩散系数为2.036×10~(-8)cm~2/s.利用计时电量法测得亚叶酸离子在该界面上转移反应的标准速率常数为2.72×10~(-3)cm/s.     

分散液液微萃取-高效液相色谱串联质谱法快速测定水迁移相中甲醛

建立了分散液液微萃取-高效液相色谱串联质谱法快速测定轻纺消费品水迁移相中痕量甲醛的分析方法。水迁移相甲醛首先与2,4-二硝基苯肼(2,4-DNPH)衍生化反应生成甲醛-2,4-二硝基苯腙,优化的反应时间为15 min,2,4-DNPH浓度为5 mmol/L,HCl浓度为50 mmol/L;在分散液液微萃取过程中,以500μL乙腈为分散剂、50μL四氯乙烯为萃取剂瞬间完成衍生物的萃取富集后,进行HPLC-ESI-MS/MS分析,分析时间为3.5 min。水相中甲醛的检测线性范围为0.001~1 mg/L,线性相关系数(R2)为0.9987,检出限为0.25μg/L。平均加标回收率范围在82.8%~113.5%,相对标准偏差范围在2.1%~9.2%,平均富集倍数为120。方法已经应用于轻纺消费品水迁移相中甲醛含量的测定。     

液/液界面电化学及其进展

液/液界面电化学及电分析化学与研究萃取和化学传感机理、相转移催化、药物释放、模拟生物膜等密切相关,近年来备受到关注. 文中结合作者课题组工作,介绍、综述该领域近十几年、尤其在液/液界面微观结构、电荷（离子与电子）转移反应及界面功能化的新进展.     

N503为载体的支撑液膜体系中汞(Ⅱ)的迁移研究

研究了以多孔聚偏氟乙烯为支撑体,N503为膜载体,煤油为膜溶剂的支撑液膜体系中Hg(Ⅱ)的迁移行为,测定了Hg(Ⅱ)与N503在煤油溶剂中的萃合物组成和条件萃取常数,考察了料液相pH值、载体浓度、料液相及反萃相中Cl-浓度等因素对Hg(Ⅱ)迁移的影响,获得Hg(Ⅱ)迁移的最佳条件:料液相pH=2.5～3.0,Cl-浓度为0.1 mol/L,载体浓度为0.706 mol/L,反萃相中Cl-浓度为0.8 mol/L.在最佳实验条件下,当Hg(Ⅱ)起始浓度为5.0×10-5 mol/L时,迁移120 min,Hg(Ⅱ)的迁移率可达99.6%.Hg(Ⅱ)在N503-煤油支撑液膜体系中的扩散层厚度δa为1.57×10-5 m,膜内扩散系数d0为7.26×10-13 m2/s,确立了Hg(Ⅱ) 的渗透系数P方程.     

Liquid Metals and Liquid Semiconductors

Numerous liquid systems have electrical properties which resemble those of crystalline and amorphous semiconductors. The existence of “semiconducting” behavior in these liquids is mostly related to a continuous transition from a metallic to a “semiconducting” state when a thermodynamic variable such as temperature, density or concentration is changed. Changes in the nature of the chemical interaction and the associated changes in the structure of the liquid are of fundamental importance for the transition to a “semiconducting” state. This will be demonstrated for the ionic liquid CsAu, for covalent liquid selenium, and for expanded liquid metals.     

液/液两相催化新进展--温控非水液/液两相催化

温控非水液/液两相催化,是指一类由两种或多种液态有机物组成的催化反应体系,其特点是体系的相态变化可通过温度来调控,即体系在高温时相互混溶呈均相,低温不溶分成两相,催化剂和产物分别处于两相,从而为解决均相催化剂分离难的问题开拓了一个新方向,是液/液两相催化研究领域最引人注目的进展之一.首次以"温控"为主线将氟两相催化作为温控液/液两相催化的一个特定类型纳入"温控非水液/液两相催化"范畴,并与其它通过温度来调控的有机液/液两相和作者提出的温控相分离催化串在一起作一较为详细的评述.     

温控液/液两相催化进展*

本文以作者在温控水/有机两相及温控非水液/液两相催化领域的研究工作为主线,对这一领域的研究进展作一评述,重点是环绕经典水/有机两相催化体系存在“应用范围受底物水溶性限制”的根本问题展开。特别是对“温控相转移催化”作了较为详细的介绍,同时,按体系介质不同,对氟两相体系、PEG两相体系、离子液体两相体系等非水液/液两相体系以及温控相分离催化分别作了阐述。     

液晶离聚物--液晶行为的研究

综述了液晶离聚物中离子的种类,位置、在链中浓度对液晶性能的影响,无论是主链还是侧链液晶离聚物,离子的种类,位置对中介区间的宽度有影响,但对中介相类型基本没有影响,当离子浓度增大到一定值时,液晶性能消失。     

Spontaneous Liquid/Liquid Displacement in a Capillary

When a two-phase column consisting of paraffin oil and silicon oil is placed in an otherwise air-filled, horizontal glass capillary, the column starts moving spontaneously. Silicon oil displaces paraffin oil, which in its turn displaces air at atmospheric conditions; a stable film of silicon oil is left at the receding silicon oil/air meniscus. The driving force for the motion is the difference in capillary pressure at the free interfaces. However, the column moves considerably more slowly than predicted by the driving forces; it appears that the forces resisting the motion at the moving liquid/liquid/solid line are much larger than one would expect on the basis of the interfacial tension and the viscosities of the two phase system. Some considerations are made on the relationship of the theory of Fowkes to our system. Also, a method for measuring low interfacial tensions between immiscible liquids is proposed.     

Liquid quasicrystals

Recent discovery of Liquid crystals with quasicrystalline symmetry (liquid quasicrystals), is reviewed. These liquid quasicrystals were created by self-organised packing of supramolecular micelles, analogous to the way by which normal quasicrystals are formed from atoms in metal alloys. This opens the way to obtaining self-assembled photonic band gap quasicrystals, and has important implications for the study of both quasicrystals and supramolecular self-assembly.     

液晶化学

液晶在近30年来受到科技界广泛关注,人们对它的性质、合成、用途进行了深入的研究,使其在现代科技领域占据重要地位。本文对液晶的性质及用途进行论述。     

LC Determination of Mono-Substituted Phenols in Water Using Liquid–Liquid–Liquid Phase Microextraction

A simple liquid–liquid–liquid microextraction device of new design was used to pre-concentrate phenols from water samples before liquid chromatographic (LC) analysis. Extraction was induced by the pH difference inside and outside an organic phase located at the interface. The pH of the donor phase outside the organic phase was adjusted to 1 with HCl whereas the acceptor phase was a basic solution at pH 13. On stirring neutral phenols were extracted into the organic solvent then back-extracted into 1 μL of basic acceptor solution suspended from the tip of a micro syringe. The acceptor phase was then withdrawn into the micro syringe and injected directly into the LC. The technique uses a low-cost disposable extraction ‘device’ and is very convenient to operate. Up to 230-fold enrichment of analytes could be achieved. This procedure could also serve as a sample clean-up step because neutral and basic compounds were not extracted into the acceptor phase. The RSD (n = 5) was better than 6.2% and the linear calibration range was from 1 to 1000 µg–L⁻¹ with r ² ≥ 0.992.Optimization of experimental conditions (rate of stirring, ionic strength of the sample solution, concentration of reagents, time of extraction, and organic solvent volume) were also examined. The method was applied to the determination of phenols in tap and well waters.Revised: 14 February and 29 March 2005