滤膜吸附结合超声辅助分散液液微萃取/高效液相色谱法测定空气中溴氰菊酯残留

建立了滤膜吸附结合超声辅助分散液液微萃取与高效液相色谱(HPLC)联用测定空气中溴氰菊酯残留的方法。空气样品用甲醇-水(1∶4)混合溶液提取,加入三氯甲烷进行微萃取,超声,离心,得到沉积相,进行HPLC分析。溴氰菊酯在5~1 000μg/L范围内线性关系良好,相关系数(r)为0.999 8,富集倍数达520倍。当空气样品的加标浓度为10,50,100μg/L时,加标回收率为78.6%~106.7%,相对标准偏差(RSD)为2.2%~4.3%。空气样品中溴氰菊酯的检出限为1μg/L,最低检出浓度为0.04μg/m~3。该方法具有简便快捷、准确灵敏、萃取效率高、有机溶剂消耗少等优点,可用于空气中溴氰菊酯残留的测定。     

蒸发辅助-悬浮固化-分散液液微萃取-高效液相色谱法测定食用菌中3种三唑类杀菌剂的残留量北大核心CSCD

提出了一种基于蒸发辅助和悬浮固化的分散液液微萃取结合高效液相色谱法测定食用菌中腈菌唑、联苯三唑醇、丙环唑等3种三唑类杀菌剂残留量的方法。将1.0 g食用菌样品切碎后放入10 mL离心管中,加入2 mL乙腈离心提取,取1 mL上清液和4 mL水置于10 mL离心管中,依次加入160μL十一酸(萃取剂,密度低于水)、150μL三氯甲烷(挥发性溶剂,密度高于水)和0.3 g氯化钠,于85℃加热8 min,十一酸在常温下固化后漂浮在样品溶液顶部,将上层固化物取出,加入250μL甲醇,溶解,过0.22μm有机滤膜。以C_(18)色谱柱为固定相,3种三唑类杀菌剂经体积比7∶3的乙腈-水混合溶液洗脱后分离,用附二极管阵列检测器的高效液相色谱仪进行检测,以香菇、杏鲍菇、木耳、银耳、海鲜菇和金针菇6种食用菌为基质绘制工作曲线。结果表明:3种三唑类杀菌剂工作曲线的线性范围为14~1 000μg·kg^(-1),检出限为4.0~5.7μg·kg^(-1);对空白样品进行加标回收试验,3种三唑类杀菌剂的加标回收率为72.3%~99.4%,测定值的相对标准偏差(n=6)均小于5.5%。     

气相色谱-质谱法结合QuEChERS方法和分散液液微萃取技术测定茭白中三唑类农药残留

采用QuEChERS方法结合分散液液微萃取技术萃取茭白中的腈菌唑、戊唑醇和苯醚甲环唑残留,并采用气相色谱-质谱法进行测定。3.000g样品经3mL乙腈超声提取1min,提取液经30mg的PSA与30mg的C_(18)混合吸附剂净化。移取800μL净化液于巴斯德吸管中,加入甲苯30μL,混匀后快速注入水2.5mL,超声45s后离心,上层有机相经无水硫酸钠除水后在DB-5MS毛细管色谱柱上分离,质谱分析中选择电子轰击离子源和选择离子监测模式。3种农药的线性范围分别为5.0~500,5.0~500,12.5~1 250μg·kg~(-1),检出限(3S/N)分别为1.4,0.86,3.0μg·kg~(-1)。加标回收率为82.7%~116%,测定值的相对标准偏差(n=5)为4.1%~15%。     

分散液-液微萃取-气相色谱-质谱法同时测定中毒样品中有毒生物碱和鼠药

建立了分散液-液微萃取(Dispersive liquid-liquid micro-extraction,DLLME)与气相色谱-质谱(GCMS)联用同时测定中毒样品中3种鼠药(毒鼠强、溴鼠灵、溴敌隆)和5种有毒生物碱(莨菪碱、东莨菪碱碱、钩吻碱、士的宁、马钱子碱)的方法。100μL萃取剂氯仿与600μL分散剂甲醇混合后,迅速注入样品,萃取过程在乳化体系中完成;以8000 r/min离心5 min,使两相分层,取下层有机相进行GC-MS分析。考察了萃取剂、分散剂的种类和体积、萃取时间、pH值及盐浓度对萃取效率的影响。在优化条件下,各目标物在水样、尿样、黄酒样的检出限为0.003~1.0μg/L,在米饭样品检出限为0.002~0.2μg/kg;各目标物低、中、高加标回收率为81.0%~110%,精密度均小于7%。本方法灵敏度高,快捷高效,适用于中毒样品中有毒生物碱和鼠药的同时测定。     

分散液液微萃取–气相色谱–质谱法测定水中3种硝基甲苯同分异构体

建立分散液液微萃取-气相色谱–质谱测定水中3种硝基甲苯同分异构体的方法。水中硝基甲苯用分散液液微萃取富集后经CD–5MS色谱柱分离,采用气相色谱质谱法测定。3种硝基甲苯同分异构体的质量浓度在0.0~40.0μg/L范围内与色谱峰面积均具有良好的线性关系,相关系数大于0.999,方法检出限为0.03~0.04μg/L。测定结果的相对标准偏差均小于2%(n=7),样品加标回收率为90.2%~95.9%。该方法操作简便,萃取效率高,有机试剂用量少,适用于环境水样中硝基甲苯的检测。     

联苯-联苯醚混合萃取剂分散液液微萃取测定饮用水中挥发性卤代烃

以联苯-联苯醚混合物为萃取剂,建立了分散液液微萃取-气相色谱电子捕获检测器测定饮用水中7种挥发性卤代烃的方法。此萃取剂为无卤素萃取剂,密度大于水,可通过离心分离,萃取过程可在3 min内完成。对萃取剂用量、分散剂种类及用量、萃取时间、萃取温度等条件进行了优化。5.00 m L水样用200μL萃取剂和0.30 m L分散剂(甲醇)的混合物进行萃取,室温下萃取30 s,7种挥发性卤代烃的萃取率≥90%,富集倍率为22.5~24.7。萃取液经DB-624毛细管柱分离,用电子捕获检测器定量检测,检出限为0.003~0.032μg/L。检测三氯甲烷的线性范围为0.500~100.0μg/L,三氯乙烯和三溴甲烷的线性范围为0.100~20.0μg/L,四氯化碳、四氯乙烯、二氯一溴甲烷、一氯二溴甲烷的线性范围为0.050~10.0μg/L。在上述线性范围内,工作曲线的相关系数≥0.998。方法的相对标准偏差在2.1%~7.6%之间,加标回收率在93.0%~102.9%之间。     

分散液液微萃取-气相色谱/质谱法测定中药甘草中邻苯二甲酸酯残留

建立了一种简单、快速、有效测定中药甘草中5种邻苯二甲酸酯(DBP、BBP、DCHP、DEHP、DNOP)的分散液液微萃取-气相色谱/质谱(DLLME-GC/MS)检测方法。甘草样品经甲醇浸泡提取,水分散和盐析后用100μL四氯化碳萃取浓缩,采用GC/MS法测定,标准曲线定量。5种目标物在1~5 000μg/L范围内呈良好的线性关系,相关系数均大于0.9990,方法的检出限和定量限在0.16~0.58μg/kg和0.34~1.92μg/kg范围。在3个加标浓度水平下的平均回收率为87.80%~120.63%,相对标准偏差小于7.43%。该方法适用于不同产地中药材甘草中环境激素邻苯二甲酸酯类残留的测定。     

悬浮固化-分散液液微萃取-气相色谱法测定野木瓜中9种有机氯农药残留量

建立了悬浮固化-分散液液微萃取-气相色谱法测定野木瓜中9种有机氯农药残留量的方法。样品经石油醚提取、浓硫酸净化、悬浮固化-分散液液微萃取法浓缩后,用气相色谱-电子捕获检测器(GC-ECD)检测,外标法定量。结果表明,9种农药含量在1~100μg/L范围内线性关系良好,相关系数R2在0.99以上,方法检出限(S/N=3)为0.01~0.07μg/kg。9种有机氯农药在1.75,7.00,28.0μg/kg 3个水平添加下,平均回收率范围为83.3%~116.7%,相对标准偏差(RSD)范围为1.5%~14%,方法已用于野木瓜中9种有机氯农药残留的测定。     

分散固相萃取-分散液液微萃取-气相色谱质谱法测定玉米和大米中氟虫腈及其代谢物的残留

建立了分散固相萃取-分散液液微萃取与气相色谱/质谱联用测定玉米和大米中痕量氟虫腈及其代谢物残留的分析方法。使用乙腈和水混合溶液作为萃取溶剂,盐析后,提取液经N-丙基-乙二胺硅烷固相萃取材料(PSA)作为吸附剂后,采用分散液液微萃取步骤将目标物从到微量四氯乙烯中。对影响分散液液微萃取效率的因素,包括萃取溶剂种类及体积、盐等条件进行了优化。在0.02~1μg/m L浓度范围内,线性关系良好(r≥0.9987)。在玉米和大米样品中氟虫腈添加浓度为1.0~25.0μg/g时,平均回收率在70.4%~95.1%之间,相对标准偏差(n=5)在2.6%~12%之间,以最低添加浓度1μg/kg作为定量限。     

分散固相萃取-分散液液微萃取结合气相色谱-三重四极杆质谱法测定茶叶中7种拟除虫菊酯类农药残留

将分散固相萃取和分散液液微萃取(d-SPE-DLLME)相结合,并与气相色谱-三重四极杆质谱(GC-MS/MS)联用,建立了快速测定茶叶中7种拟除虫菊酯类农药残留的方法。样品经乙腈提取,N-丙基乙二胺(PSA)和多壁碳纳米管(MWCNTs)净化,四氯化碳(CCl_4)浓缩萃取后,采用GC-MS/MS进行分析。以全发酵红茶为基质,考察了提取剂种类、萃取剂的种类和体积、分散剂体积以及萃取时间对萃取效率的影响。以乙腈为提取剂进行分散固相萃取,在进行分散液液微萃取时,以200μL CCl4为萃取剂,1 m L乙腈为分散剂,萃取时间为1 min。结果表明,7种拟除虫菊酯类农药在10~500μg/kg浓度范围内线性关系良好,定量下限为1.0~10.0μg/kg。7种农药在4种茶叶(红茶、绿茶、乌龙茶和黑茶)中4个添加水平下的平均回收率为75.4%~113.6%,相对标准偏差(RSD,n=5)不大于8.8%。该方法具有简单、快速、成本低、检出限低的特点。应用所建立的方法对12种市售茶叶样品进行检测,结果满意。     

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