键合石墨化碳黑作为毛细管气相色谱固定相的研究

将石墨化碳黑衍生物键合在毛细管柱上,对烷烃、醇、芳香化合物、酮类等物质进行分离考察,其色谱性能较好.键合石墨化碳黑作为毛细管气相色谱固定相使用寿命增加,可做进一步研究.     

新型溶胶-凝胶气相色谱柱:聚甲基苯基硅氧烷柱、Carbowax柱及PEG-Silane柱

采用聚甲基苯基硅氧烷、Carbowax 20M、PEG-silane为固定相制取了溶胶-凝胶气相色谱毛细管柱在这些色谱柱上脂肪酸、酚类、胺和苯胺类、醇、醛等各类化合物都得到很好的分离一采用这些固定相的溶胶一凝胶柱对化合物的分离也表现出很好的重现性。溶胶-凝胶法制柱对各类固定相是普遍适用的方法．     

新型季磷离子液体气相色谱柱的制备及应用

选择季磷型离子液体为气相色谱固定相,采用静态法将其涂渍于纳米级SiO2预处理的毛细管内壁上制备成毛细管气相色谱柱.考察了此固定相的基本色谱性能和极性,并详细研究了其对多种化合物的分离性能和保留特点.研究表明,此该离子液体色谱柱的柱效为1381 plates/m,极性为559.6,与商品化的聚乙二醇(PEG20M)和硝基对苯二甲酸改性的聚乙二醇(FFAP)柱的极性相近.此固定相对给质子体化合物的保留作用明显强于PEG20M,并且其对芳香化合物的间位和对位异构体的分离选择性明显优于自制的PEG20M.此固定相对芳香位置异构体、烷烃、多环芳烃、氯苯、醇类等均具有较好的分离效果.     

硅藻土载负葫芦[7]脲气相色谱固定相的制备及其性能评价

在酸性条件下,将自制的葫芦[7]脲均匀地涂覆到102白色硅藻土担体上,制得葫芦[7]脲气相色谱固定相.采用红外光谱、质谱、元素分析和热重分析表征了葫芦[7]脲在载体表面的结构.利用相关探针测定了新固定相的麦氏常数,表征了其基本色谱性能.考察了葫芦[7]脲气相色谱固定相填充柱对芳香烃、卤代烃、醇、酮、酯及硅氧烷的分离能力.结果表明,葫芦[7]脲固定相热稳定性高,柱色谱性能稳定,对较广泛的化合物尤其对高沸点的酯类及硅氧烷类化合物显示出良好的色谱分离能力(7 min内分离),作为气相色谱固定相有较好的应用前景.初步讨论了葫芦[7]脲固定相对上述化合物的分离机理.     

二维气相色谱在微量分析中的应用

 〕为探索溶剂或单体中微量杂质分析方法，在SP-2305E型色谱仪上设计了二维气相色谱流程，采用在线微型六通阀进行流路切换，用微型中间陷阱进行“再进样”。用自制石墨化碳黑毛细管柱和不同极性的填充预柱，对氯甲烷中微量杂质进行了分离和定性。     

多壁碳纳米管的纯化

用900℃高温氢气处理以及5 mol/L盐酸回流的方法，纯化了一种由甲烷在Ni- Mg-O催化剂上裂解生长的多壁碳纳米管（MWCNTs），考察了不同纯化阶段MWCNTs的 吸水率、比表面积、Ni和Mg残留量以及在不同温度下苯、正己烷、乙醇、丙酮四种 化合物在MWCNTs填充色谱柱上的脱附率的变化，并用透射电镜观察了MWCNTs的形态 。结果表明，高温氢气处理可去除MWCNTs的无定形碳和表面极性基团，使其比表面 积和吸水率减小，同时可打开MWCNTs端口。高温氢气处理后，再用盐酸回流即容易 去除MWCNTs中单用盐酸回流方法无法去除的Ni.经过纯化的MWCNTs的吸水率远小于 活性碳，比Carbopack B稍大，比表面积和Carbopack B相近。苯、正己烷、己醇、 丙酮四种化合物在纯化的MWCNTs填充色谱柱上的脱附率和Carbopack B的相同。经 纯化的MWCNTs的Ni残留量为30 μg/g，Mg残留量低于检测限（10 μg/g）。由于管 腔的存在，纯化的MWCNTs对有机物的保留能力大于Carbopack B。它可以作为气相 色谱固定相和吸附挥发性有机物的吸附剂。     

C_(18)反相色谱固定相的制备及性能评价

以粒径10μm硅胶为基质,与1,6-六亚甲基二异氰酸酯和十二醇反应制得新型C_(18)反相色谱固定相。热失重结果表明,所制得的固定相在200℃以内热稳定性良好。扫描电镜结果表明:硅胶在改性前后没有损坏,颗粒完整,适合于色谱柱的填装。该固定相对联苯的静态吸附在4h时达到平衡,吸附行为符合Langmuir吸附等温式。用芳香烃和极性化合物对固定相的分离性能进行评价,结果表明所合成的固定相具有良好的色谱性能。     

甘脲用作气相色谱固定相的色谱性能研究

甘脲具有双环双脲结构,既是质子给体,又是质子受体,能与溶质产生氢键作用等多种作用力。本文制备了以甘脲作为固定相的填充柱,并对它的色谱性能进行了研究。结果表明:甘脲固定相热稳定性高、柱性能稳定,是一种良好的气相色谱固定相。该固定相对烷烃、卤代烃、芳烃、醇、酯、酮、酸、胺等类物质具有良好的分离能力,尤其是对位置异构体(如二取代苯位置异构体)有较好的分离选择性。本文还初步探讨了甘脲固定相的分离机理。     

甘脲和羟基葫芦[6]脲气相色谱固定相的制备及其色谱分离性能比较研究

甘脲是羟基葫芦[6]脲(HOCB6)的前体, 本文设计了一种在酸性条件下均匀涂渍固定液的新方法, 首次将甘脲和羟基葫芦[6]脲用作气相色谱固定相. 将甘脲和HOCB6填装成气相色谱填充柱后, 以烷烃、卤代烃、芳香烃、醇、酮、酯、酸、胺等物质为探针, 用复杂样品花露水对它们的色谱分离性能进行了比较研究. 结果表明, 甘脲和HOCB6 都是良好的气相色谱固定相, 热稳定性高, 柱性能稳定. 两种固定相对以上溶质探针都有较好的分离能力, HOCB6固定相(PSP)与甘脲固定相(GSP)相比较, 总体上具有更好的分离选择性, 对难分离的芳香族位置异构体(如二甲苯、甲基苯胺)具有良好的分离能力, 显示出较高的立体选择性, 对花露水中的高沸点组分有较好的分离效果. 上述研究也表明, 由于溶质在载气中传质比葫芦脲内腔快得多, 全包结尽管有利于提高分离选择性, 但展宽后的柱效不理想; 适当的高柱温既保留了部分包结作用, 同时存在端口协同作用, 能兼顾高选择性和高柱效.     

硅烷基咪唑双三氟甲烷磺酰亚胺离子液体气相色谱固定相的性能评价

以双三氟甲烷磺酰亚胺离子([NTf₂]^-)为阴离子,合成阳离子烷基取代不同(C1、C2和C4)的硅烷基咪唑离子液体,以其为固定相制备气相色谱填充柱。 硅烷基咪唑离子液体为强极性固定相;阳离子结构影响固定相的热稳定性、极性和分离性能。 在这些离子液体固定相中,1-丁基-3-[(3-三甲氧基硅基)-丙基]咪唑双三氟甲烷磺酰亚胺([PBIM]NTf₂)对Grob试剂分离性能较好。 利用溶剂化作用参数模型,评价[PBIM]NTf₂固定相特性,研究固定相-组分分子之间相互作用机制;同时考察[PBIM]NTf₂色谱柱对不同类型化合物的分离性能。 结果表明,[PBIM]NTf₂固定相主要作用力是氢键碱性和偶极作用,对烷烃、醇、酯和胺等不同类型的样品组分表现出良好的分离能力。     

Evaluation of multi-walled carbon nanotubes as gas chromatographic column packing

Purified multi-walled carbon nanotubes (PMWCNTs), activated charcoal and graphitized carbon black (Carbopack B) were used as column packing materials to compare their separation ability and other gas chromatographic behavior for aromatic hydrocarbons, alkanes, halogenated hydrocarbons, alcohols, ketones, esters, and ethers. The results show that PMWCNTs can be an excellent gas chromatographic packing material. Compared to Carbopack B with the same surface area, PMWCNTs had a stronger retention ability, a more homogenous surface and smaller theoretical plate numbers. Polar compounds can present symmetric peaks on PMWCNTs. PMWCNTs were found to be an interesting alternative adsorbent to activated charcoal and Carbopack B as gas chromatographic column packing material for volatile compounds, especially those with relatively low boiling points.     

A homochiral porous organic cage with large cavity and pore windows for the efficient gas chromatography separation of enantiomers and positional isomers

Porous organic cages composed of discrete cage molecules have attracted considerable recent attention as gas adsorption materials and separation media. In this study, we report a homochiral porous organic cage CC5 with a large cavity and pore windows as a novel stationary phase for high‐resolution gas chromatographic separations. The capillary column was prepared by a static coating method. A large number of racemic compounds have been resolved on the coated capillary column, including derivatized amino acids, alcohols, alcohol amines, esters, ethers, ketones, and epoxides. It is interesting that the CC5‐coated capillary column exhibits significant chiral recognition complementarity to a commercial β‐DEX 120 column and a previously reported homochiral porous organic cage CC3‐R‐coated column, which could expand the range of the analytes amenable to separation on porous organic cage‐based capillary columns. Moreover, the fabricated column also shows excellent selectivity for the separation of positional isomers, including the challenging ethylbenzene and xylene isomers. Experimental results demonstrate an excellent separation performance and stability of the CC5‐coated column, making it promising for gas chromatography applications.     

顶空气相色谱-质谱法同时测定蜂蜜中57种挥发性有机溶剂残留

建立了顶空气相色谱-质谱(HS-GC/MS)同时测定蜂蜜中57种挥发性有机溶剂(包括烷烃类、芳香烃类、醇类、酮类、酯类、醚类)残留量的分析方法。蜂蜜样品在密封的顶空瓶中用水溶解后,在顶空仪中于80 ℃下平衡30 min,使气-液两相达到动态平衡。采用DB-624毛细管色谱柱(60 m×0.25 mm×1.40 μm)对57种有机溶剂进行分离,GC/MS测定,外标法定量。该方法对于烷烃类、芳香烃类和醚类挥发性有机溶剂在0.005～0.2 μg、酯类0.05～2.0 μg、酮类0.5～20 μg、醇类2.5～100 μg范围内线性关系良好,相关系数均大于0.996。对于烷烃类、芳香烃类和醚类挥发性有机溶剂在1.0～20 μg/kg、酯类10～200 μg/kg、酮类100～2000 μg/kg、醇类500～10000 μg/kg添加范围内的平均添加回收率为61.0%～113.1%,相对标准偏差为1.9%～9.8%。对于烷烃类、芳香烃类和醚类挥发性有机溶剂的检出限为1.0 μg/kg、酯类10 μg/kg、酮类100 μg/kg、醇类500 μg/kg。该方法操作简单、快速,灵敏度和准确度高,适用于蜂蜜样品中多种挥发性有机溶剂残留量的同时检测。     

Evaluation of multi-walled carbon nanotubes as an adsorbent for trapping volatile organic compounds from environmental samples

A type of purified multi-walled carbon nanotubes (PMWCNTs) prepared by catalytic decomposition of methane, with a surface area of 98 m2/g, was evaluated as an adsorbent used for tapping volatile organic compounds (VOCs). The performance in evaluation was based on breakthrough volumes (BTVs) and recoveries of selected VOCs. PMWCNTs were also used as a trap packing material to adsorb VOCs purged from spiked water sample. Due to their porous structure, PMWCNTs were found to have much higher BTVs than that of Carbopack B, a graphitized carbon black with the same surface area as PMWCNTs. The recoveries of the tested VOCs trapped on PMWCNTs ranged from 80 to 110%, and not affected by the humidity of purge gas. The results indicate that PMWCNTs are a potential useful adsorbent for direct trapping VOCs from air samples and may be a supplement to VOCARB 3000, a commercially available trap, in purge-and-trap system to preconcentrate VOCs from water samples.     

液晶冠醚、碳纳米管、水溶性杯芳烃在分析化学中的应用

综述了液晶冠醚、碳纳米管、水溶性杯芳烃在分析化学中应用的新进展。介绍了液晶冠醚在离子传输、分子识别、色谱分析、LB膜等各方面的应用;讨论了碳纳米管在扫描显微镜探针针尖、气体传感器、化学修饰电极和化学分离与检测方面的应用,以及水溶性杯芳烃在光度法、电化学、色谱分离方面的应用。     

Separating Ability of Some Polar Mobile Phases in Reverse Phase High Performance Liquid Chromatography

Abstract

Homologous series of n-alkanes, n-alcohols, ethers, esters, amides and ketones were studied as solutes. Methanol, acetonitrile, ethanol, dioxane, 2-propanol and tetrahydrofuran were mobile phases. Spherisorb ODS columns with light and heavy octadecyl coatings were used. Methanol and acetonitrile were found to be the most selective solvents for reverse phase separation. The polar amides, alcohols, and ketones behaved differently from nonpolar solutes in acetonitrile mobile phases. Results were interpreted with the solvophobic theory.     

Glass capillary gas chromatography of chlorinated methyl acetates,propanoates and butanoates on Carbowax 20M and SE-30 columns

Summary The gas chromatography of all chlorinated methyl acetates, methyl propanoates and methyl mono- and dichlorobutanoates has been studied on Carbowax 20M and SE-30 glass capillary columns under various running conditions. The order of elution on a non-polar column was largely determined by the boiling point of esters, whereas on a polar column it was much influenced by the structure of compounds. Complete separation of the combined mixture of all 27 compounds could not be achieved, however, methyl 3,3-dichlorobutanoate was the only ester overlapped on both columns in spite of the various column temperatures used. The best separation of the mixture was on Carbowax 20M with a temperature program from 50°C at 8°C/min, isothermal running conditions leading either to poor separation of volatile components or long analysis time and broad peaks of higher chlorinated esters. The relative retention times for compounds at the various column temperatures are given and the retention order on a polar and on a non-polar column discussed.     

Applications of ethylammonium and propylammonium nitrate solvents in liquid-liquid extraction and chromatography

Ethyl- and propylammonium nitrate are novel ionic solvents, liquid at room temperature, suitable for use as selective solvents for the isolation of analytes containing proton donor functional groups (alcohols, amines, phenols, carboxylic acids, etc.) by liquid-liquid distribution. These solvents form immiscible solvent pairs with non-polar aliphatic and aromatic hydrocarbons, ethers and alkyl halide solvents (e.g., methylene chloride, chloroform). Analytes can be recovered from the ionic solvents by back-extraction into ah organic solvent after dilution with water or pH buffer or, preferably, by extractive derivatization when gas chromatography is used for the analyses, avoiding the accumulation of salt on the column that results in poor baseline stability. Alkylation, acylation and particularly silylation are suitable methods for extractive derivatization using standard reaction conditions. Applications are presented for the isolation of polar analytes from an urban dust, shale oil and urine samples and for the determination of low-molecular-weight alcohols in gasahol and glycerol in soap. Liquid-liquid chromatographic systems with the liquid organic salt as stationary phase can be used to predict distribution constants for a particular separation and for the separation of polar solutes, particularly isomeric compounds possessing a proton donor functional group.     

Gas chromatographic study of the urea—Cetyl alcohol adduct and its components

Summary As part of the gas chromatographic study of inclusion compounds, the behaviour of cetyl alcohol (the guest component in the inclusion compound with urea) and its properties as a stationary phase were followed. Measurements were carried out over a temperature range of 40–100°C with a wide selection of substances including aliphatic and aromatic hydrocarbons, halocarbons, alcohols, esters, ethers, carbonyl compounds, amines and organic acids. The experimental retention data were interpreted from the point of view of possible interactions and the contributions from the individual intermolecular forces were evaluated. The results indicated that cetyl alcohol could be used as a stationary phase over a range of 50–90°C for rapid analysis of many non-polar, medium and strongly polar substances.Dedicated to the 70th birthday of ProfessorA. A. Zhukhovitskii.