离子液体液-液萃取-高效液相色谱测定水中酚类化合物

建立了离子液体1-丁基-3-甲基咪唑六氟磷酸盐([C4mim][PF6])液-液萃取-高效液相色谱测定水中酚类化合物的方法.研究了水相pH值、萃取时间、水相体积及盐的浓度对萃取的影响.最佳萃取条件分别为:水相pH值为5,萃取时间为40 min,水相体积为60 mL.对比了离子液体对1-辛醇对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的富集效率.在最佳条件下,离子液体对5种酚的富集倍率在9～151之间,方法对苯酚、4-硝基苯酚、2-硝基苯酚、2,4-二甲基苯酚和双酚A的检出限分别为:2.0、0.9、0.3、1.8和1.1 μg/L.将该方法应用于自来水、河水、湖水和污水的检测,回收率为87.9%～109.9%.     

超声辅助分散液-液微萃取/高效液相色谱联用富集分析环境水样中邻苯二甲酸酯类化合物

建立了超声波辅助分散液-液微萃取(DLLME)与高效液相色谱(HPLC)联用对环境水样中痕量邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)和邻苯二甲酸二辛酯(DOP)富集分离测定的方法,优化了色谱分离条件,考察了萃取剂与分散剂的种类与用量、萃取时间和离子强度对超声辅助DLLME/HPLC的影响。在优化实验条件下,邻苯二甲酸酯色谱峰面积与其浓度在1.00～100μg.L-1范围内呈良好的线性关系,相关系数均大于0.996,平均加标回收率为91%～103%,相对标准偏差(RSDs,n=5)为2.0%～6.8%,5种邻苯二甲酸酯类化合物的检出限(S/N=3)分别为0.08、0.04、0.03、0.01、0.07μg.L-1。建立的方法用于环境水样中邻苯二甲酸酯的测定,平均加标回收率为85%～119%,RSDs(n=3)为2.3%～11.1%。该方法适用于环境水样中痕量邻苯二甲酸酯类化合物的富集分析。     

超声辅助分散液液微萃取-高效液相色谱测定水样中的4种邻苯二甲酸酯类增塑剂

建立了采用超声辅助分散液液微萃取技术结合高效液相色谱法(UA-DLLME-HPLC)对4种邻苯二甲酸酯(PAEs)进行富集、检测的方法,并成功应用于实际水样分析。实验中采用富集因子来评价萃取效率,考察并优化了影响萃取效率的主要因素,包括萃取剂类型和用量、分散剂类型和用量、超声时间、离子强度、萃取时间和pH值等。结果表明: 在最佳萃取条件下,该法对4种PAEs（邻苯二甲酸二甲酯、邻苯二甲酸二乙酯、邻苯二甲酸二丁酯和邻苯二甲酸二正辛酯）具有较高的富集能力,富集因子分别为71、144、169和159;检出限分别为3.78、1.77、3.07和3.30 μg/L。对实验室自来水、某品牌矿泉水以及湖水分别加标50、200及500 μg/L的回收率为82.99%～114.47%,相对标准偏差为1.93%～8.31%。该法简便、快速、环保,可以用于测定实际水样中的PAEs类增塑剂。     

分散固相萃取-气相色谱-质谱法测定罐头食品中6种邻苯二甲酸酯

以正已烷为萃取溶剂,采用乙二胺-N-丙基硅烷(PSA)固相材料分散净化技术,以气相色谱-质谱(GC-MS)在选择离子监测模式下测定罐头食品中邻苯二甲酸二丁酯(DBP)、邻苯二甲酸苄基丁基酯(BBP)、邻苯二甲酸二乙基己基酯(DEHP)、邻苯二甲酸二辛酯(DNOP)、邻苯二甲酸二异壬酯(DINP)、邻苯二甲酸二异癸酯(DIDP).该方法在0.1～5.0 mg·L-1(DBP、BBP、DEHP、DNOP)、0.5～25.0 mg·L-1(DINP、DIDP)范围内呈线性关系,相关系数大于0.995.方法测定限(S/N=10):DBP、BBP、DEHP、DNOP为0.01 mg·kg-1,DINP、DIDP为1.0 mg·kg-1.以罐头食品为基体,加入3种不同浓度的6种邻苯二甲酸酯标准溶液做回收试验,测得回收率在85%～130%之间,相对标准偏差＜10%.     

高效液相色谱-串联质谱法检测食品中6种邻苯二甲酸酯

建立了食品中邻苯二甲酸二丁酯(DBP)、邻苯二甲酸丁基苄基酯(BBP)、邻苯二甲酸二已酯(DEHP)、邻苯二甲酸二正苄酯(DNOP)、邻苯二甲酸二异壬酯(DINP)、邻苯二甲酸二异癸酯(DIDP)6种邻苯二甲酸酯的高效液相色谱-串联质谱检测方法。试样用正己烷∶甲基叔丁基醚∶乙腈(体积比为50∶45∶5)提取并冷冻离心去除脂肪,收集溶剂层并挥干,加入0.5g乙二胺-N-丙基硅烷(PSA)并用2mL乙腈溶液混匀,冷冻离心后过膜备用。优化分离与检测的最佳条件,采用电喷雾正离子电离(ESI+)模式和多离子反应监控(MRM)模式,外标法进行定量。该方法中DBP、BBP、DEHP、DNOP在0.1～3.0mg/L之间,DINP和DIDP在1.0～30.0mg/L之间的线性相关系数R2>0.995;检测限分别为:DBP 0.02mg/L,BBP、DEHP和DNOP 0.005mg/L,DINP和DIDP 0.10mg/L。在添加水平为0.2、0.5、1.0mg/kg时的平均加标回收率和相对标准偏差范围符合食品检测要求。该方法简便、灵敏、精确,适用于检测食品中6种邻苯二甲酸酯残留。     

分散液液微萃取富集土壤中的二嗪磷和甲拌磷残留

建立了基于离子液体1-辛基-3-甲基咪唑六氟磷酸盐的分散液液微萃取富集土壤中二嗪磷和甲拌磷的方法。实验确定了萃取优化条件:萃取剂为400μL 1-辛基-3-甲基咪唑六氟磷酸盐离子液体,分散剂为4mL甲醇,液固比(溶液体积与样品质量之比)为4∶1,微波温度为50℃,微波时间为8min。将建立的萃取方法与高效液相色谱法结合,应用于实际土壤样品的测定,结果表明该方法能对土壤中的二嗪磷和甲拌磷进行高效萃取与富集,方法快速简便。     

固相萃取-气相色谱法测定纺织品中的邻苯二甲酸酯类环境激素

采用索氏提取法以正己烷为提取溶剂提取纺织品中的邻苯二甲酸酯类物质(PAEs),以强阴离子交换固相萃取(SPE)小柱净化本底杂质并富集待测物,建立了纺织品中10余种PAEs环境激素的同时测定方法。采用的固相萃取条件为:5 mL正己烷活化、3 mL异辛烷淋洗、2 mL含15%乙酸乙酯的正己烷溶液洗脱。SPE能有效地对提取液进行富集浓缩,同时对纺织物提取液中的杂质净化效果突出。该方法准确可靠,重现性好,在5~100 mg/kg 添加水平,PAEs各化合物的回收率为86.3%~102.7%,相对标准偏差（RSD）一般小于5%。检测的10余种PAEs中邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丙酯(DPrP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二戊酯(DAP)、邻苯二甲酸丁基苄基酯(BBP)、邻苯二甲酸二环己酯(DCHP)、邻苯二甲酸二(2-乙基己基)酯(DEHP)、邻苯二甲酸二正辛酯(DNOP)的方法检出限小于1mg/kg,邻苯二甲酸二异壬酯(DINP)与邻苯二甲酸二异癸酯(DIDP）的方法检出限分别为1.74 mg/kg和1.55 mg/kg。     

气相色谱-质谱法测定玩具中邻苯二甲酸酯类增塑剂

采用二氯甲烷作为萃取溶剂,超声提取塑料玩具和毛绒玩具中的6种增塑剂,提出了邻苯二甲酸二正丁酯(DBP)、邻苯二甲酸(2-乙基己基)酯(DEHP)、邻苯二甲酸二异壬酯(DINP)、邻苯二甲酸丁苄酯(BBP)、邻苯二甲酸二正辛酯(DNOP)和邻苯二甲酸二异癸酯(DIDP)等6种增塑剂的气相色谱-质谱分析方法。在选定的试验条件下,BBP、DBP、DEHP和DNOP可以完全分离,通过比较保留时间、色谱图和峰面积(m/z 149),可实现以上4种物质的定性和定量分析。而DIDP和DINP的峰重叠,需通过选择m/z293,307质谱峰进行定量分析。结果表明方法能够有效地检测出玩具中邻苯二甲酸酯类增塑剂的含量。     

分散液液微萃取-气相色谱法测定水样中甲拌磷农药

建立了基于分散液液微萃取(DLLME)的新型样品前处理方法,并采用气相色谱/氢火焰离子化检测器对水样中痕量的甲拌磷农药进行了测定。考察了影响分散液液微萃取的因素包括萃取溶剂、分散剂、样品体积、萃取温度和离心速度等。在最佳实验条件下,对甲拌磷的富集倍数达到300倍;检出限为0.001μL/L;方法的线性范围为0.01~10μL/L,R2为0.9986;相对标准偏差为6.65%;回收率为104%。将分散液液微萃取法与单滴液相微萃取和离子液体-液相微萃取方法进行了对比,结果表明,分散液液微萃取技术具有操作简单、快捷(前处理时间小于5 min)、富集效果好、回收率高等优点。同时预言,将离子液体与分散液液微萃取结合,将会产生更加满意的结果。     

中空纤维分散液膜富集稀土元素

采用2-乙基己基膦酸单-2-乙基己基酯(HEHEHP)-正庚烷为萃取剂,盐酸为反萃取剂,中空纤维膜作支撑膜,研究中空纤维分散液膜技术富集稀土镱(Yb~(3+))离子。考察了体系物性:反萃分散相中反萃剂浓度、萃取剂浓度、萃取剂与反萃剂体积比、料液相p H值、稀土离子浓度;流体流动状态:反萃分散相与料液相流速变化等因素对富集稀土离子的影响。中空纤维分散液膜富集Yb~(3+)的最佳条件为:萃取剂浓度为0.25 mol/L,反萃取剂HCl浓度为4.00 mol/L,萃取剂与反萃剂体积比为10∶40,料液相p H=2.80,稀土离子浓度为0.025 mol/L。反萃分散相体积流量和料液相体积流量较小时,萃取率随流量的增加呈现逐渐增大的趋势。若两相体积流量过大,反萃过程进行不完全,萃取率反而下降。研究结果表明,中空纤维分散液膜技术可实现稀土离子的有效富集。     

Potential-modulation spectroscopy at solid/liquid and liquid/liquid interfaces.

Potential-modulation spectroelectrochemical methods at solid/liquid and liquid/liquid interfaces are reviewed. After a brief summary of the basic features and advantages of the methods, practical applications of potential-modulation spectroscopy are demonstrated using our recent studies of solid/liquid and liquid/liquid interfaces, including reflection measurements for a redox protein on a modified gold electrode and fluorescence measurements for various dyes at a polarized water/1,2-dichloroethane interface. For both interfaces, the use of linearly polarized incident light enabled an estimation of the molecular orientation. The use of a potential-modulated transmission-absorption measurement for an optically transparent electrode with immobilized metal nanoparticles is also described. The ability of potential-modulated fluorescence spectroscopy to clearly elucidate the charge transfer and adsorption mechanisms at liquid/liquid interfaces is highlighted.     

Extensible automated dispersive liquid–liquid microextraction

In this study, a convenient and extensible automated ionic liquid-based in situ dispersive liquid–liquid microextraction (automated IL-based in situ DLLME) was developed. 1-Octyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide ([C₈MIM]NTf₂) is formed through the reaction between [C₈MIM]Cl and lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf₂) to extract the analytes. Using a fully automatic SPE workstation, special SPE columns packed with nonwoven polypropylene (NWPP) fiber, and a modified operation program, the procedures of the IL-based in situ DLLME, including the collection of a water sample, injection of an ion exchange solvent, phase separation of the emulsified solution, elution of the retained extraction phase, and collection of the eluent into vials, can be performed automatically. The developed approach, coupled with high-performance liquid chromatography–diode array detection (HPLC–DAD), was successfully applied to the detection and concentration determination of benzoylurea (BU) insecticides in water samples. Parameters affecting the extraction performance were investigated and optimized. Under the optimized conditions, the proposed method achieved extraction recoveries of 80% to 89% for water samples. The limits of detection (LODs) of the method were in the range of 0.16–0.45 ng mL⁻¹. The intra-column and inter-column relative standard deviations (RSDs) were <8.6%. Good linearity (r > 0.9986) was obtained over the calibration range from 2 to 500 ng mL⁻¹. The proposed method opens a new avenue for automated DLLME that not only greatly expands the range of viable extractants, especially functional ILs but also enhances its application for various detection methods. Furthermore, multiple samples can be processed simultaneously, which accelerates the sample preparation and allows the examination of a large number of samples.     

Surface-functionalized ionic liquid crystal-supported ionic liquid phase materials: ionic liquid crystals in mesopores

The influence of confinement on the ionic liquid crystal (ILC) [C(18)C(1)Im][OTf] is studied using differential scanning calorimetry (DSC), polarized optical microscopy (POM), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The ILC studied is supported on Si-based powders and glasses with pore sizes ranging from 11 to 50 nm. The temperature of the solid-to-liquid-crystalline phase transition seems mostly unaffected by the confinement, whereas the temperature of the liquid-crystalline-to-liquid phase transition is depressed for smaller pore sizes. A contact layer with a thickness in the order of 2 nm is identified. The contact layer exhibits a phase transition at a temperature 30 K lower than the solid-to-liquid-crystalline phase transition observed for the neat ILC. For applications within the "supported ionic liquid phase (SILP)" concept, the experiments show that in pores of diameter 50 nm a pore filling of α>0.4 is sufficient to reproduce the phase transitions of the neat ILC.     

Ionic liquid/ionic liquid dispersive liquid-liquid microextraction

In this article, a novel and simple microextraction method, termed ionic liquid/ionic liquid dispersive liquid–liquid microextraction (IL/IL‐DLLME), has been designed and developed for the rapid enrichment and analysis of environmental pollutants. Instead of using hazardous organic solvents, two kinds of ILs, hydrophobic IL and hydrophilic IL, were used as extraction solvent and disperser solvent in IL/IL‐DLLME step, respectively. Permethrin and biphenthrin, two of the often‐used pyrethroid pesticides, were used as model compounds. Factors that may affect the enrichment efficiencies were investigated and optimized in detail. Under optimum conditions, permethrin and biphenthrin exhibited a wide linear relationship over the range 1–100 μg/L. For permethrin and biphenthrin, the precisions were 4.65–7.78%, and limits of detection were found to be 0.28 and 0.83 μg/L, respectively. Satisfactory results were achieved when the present method was applied to analyze the target compounds in real‐world water samples with spiked recoveries over the range 84.1–113.5%. All these facts indicated that IL/IL‐DLLME is a simple and rapid alternative for the enrichment and analysis of environmental pollutants and will have a wide application perspective in the future.     

Broad liquid crystalline temperature range of ferroelectric liquid crystals

Novel ferroelectric liquid crystalline compounds, containing the (S)-2-methyl-l -butyl (4-hydroxybiphenyl-4'-carbonyloxy)biphenyl-4-carboxylate mesogenic group and an oligooxyethylene spacer, were synthesized. The mesomorphic properties of these materials were investigated by differential scanning calorimetry (DSC), optical polarizing microscopy (POM) and powder X-ray diffraction measurement. The results indicate that all members of this series exhibit a very broad temperature mesophase range (reaching a maximum around 210°C) including a blue phase (BP), cholesteric (Ch), twist grain boundary A (TGB_A), chiral smectic C (S*_c), and smectic X (S_x) phases. The mesomorphic properties are discussed and a comparison is made with three phenyl rings of ester core analogues.     

Lyotropic liquid crystalline phases formed in an ionic liquid

Lyotropic liquid crystalline phases of an amphiphilic block copolymer are constructed and characterized in an ionic liquid with comparison of component and temperature effects.