(R)‐N,N,N‐Trimethyl‐2‐Aminobutanol‐Bis(Trifluoromethane‐Sulfon)Imidate Chiral Ionic Liquid Used as Chiral Selector in HPCE,HPLC, and CGC

Abstract

In this work, the (R)‐N,N,N‐trimethyl‐2‐aminobutanol‐bis(trifluoromethanesulfon)imidate chiral ionic liquid was first used in chromatography and exhibited a excellent chiral recognition ability in high performance capillary electrophoresis (HPCE), high performance liquid chromatography (HPLC), and capillary gas chromatography (CGC), which also showed for the first time that chrial ionic liquid was an effective chiral selector in HPCE and HPLC. The compounds that have been separated using this chiral ionic liquid at least included alcohol, amine, acid, and amino acid, et al. enantiomers. As the chiral ionic liquid can be easily synthesized from relatively inexpensive materials, it should have a great potentiality for chiral separation in chromatographic science.     

Advances in Capillary Chromatography

  Abstract：Capillary columns are used in both capillary liquid chromatography and capillary electrochromatography. The design for capillary liquid chromatography is discussed in comparison with capillary gas chromatography. The difference of diffusion coefficient in gas and liquid phase is a key role. The study for obtaining a high performance capillary liquid chromatography is discussed. Capillary electrochromatography is recently interesting for its instinct ability to realize a high performance chromatography. Capillary electrochromatography with and without pressurized flow is reviewed briefly. Instrumentation for capillary electrochromatography with pressurized flow is discussed. The port of splitting, and gradient elution of both solution and potential are described. The new findings of both the variation of column resistance and capacity factor according to the value of applied electric voltage are also discussed.     

Capillary liquid chromatography-mass spectrometry and micellar electrokinetic chromatography as complementary techniques in environmental analysis

Applications of capillary electrophoresis (CE) and capillary liquid chromatography (LC) to environmental analysis have been limited. In this work we present applications of micellar electrokinetic chromatography (MEKC) to the analysis of environmental matrices for synthetic dyes. Separations obtained by capillary LC are compared with those obtained under MEKC for seven selected dyes. Both techniques are capable of resolving the subject compounds at high efficiency. Recovery data for spiked water and soil matrices were obtained for four dyes using solid-phase extraction cartridges and disks with determination by MEKC-UV detection. Both pH adjustment via acid and ion-pairing via a cationic surfactant were investigated for isolating dyes. Capillary LC detection was by continuous-flow liquid secondary ion mass spectrometry (CF-LSI-MS) whereas MEKC used UV detection (214 nm). Application of peak-profiling at high mass resolution is illustrated with the capillary LC-MS technique. Interfacing capillary LC under CF-LSI-MS using the coaxial arrangement is easier than interfacing CE with this arrangement. MEKC provides a powerful screening and determinative technique, while capillary LC-MS provides a confirmatory tool.     

色谱分析中离子液体的应用及其测定

离子液体作为一种优良的溶剂越来越受到人们的关注。由于离子液体特殊的物理化学性质使其在色谱分析中也得到了较广泛的应用。本文综述了离子液体在气相色谱、高效液相色谱和毛细管电泳中的应用,其中包括离子液体作为气相色谱的固定相、高效液相色谱的固定相及流动相添加剂和毛细管电泳的电解质添加剂等,并对离子液体的色谱分离检测作了详细介绍。     

Preparation and application of organic-silica hybrid monolithic capillary columns

Organic-silica hybrid monolithic columns have drawn more and more attention due to the ease of preparation and good mechanical stability in recent years. Many synthetic approaches have been developed and a variety of hybrid monolithic capillary columns have been prepared. The sol-gel process is well recognized in the fabrication of hybrid monolithic columns, which can be mainly classified as one-step, acid/base two-step procedures. The new approaches such as the "one-pot" and nano-scaled inorganic-organic hybrid reagent of polyhedral oligomeric silsesquioxane used as a cross-linker have also emerged for the preparation of hybrid monolithic columns. The applications of the organic-silica hybrid monolithic capillary columns for capillary electrochromatography, micro high-performance liquid chromatography, solid-phase micro-extraction and enzymatic reactor etc. are included in this review.     

高效液相色谱法和毛细管电泳法测定甘草制品中甘草酸的含量

分别用高效液相色谱法（ＨＰＬＣ）、毛细管区带电泳法（ＣＺＥ）、胶束电动毛细管色谱法（ＭＥＣＣ）测定了甘草制品中甘草酸的含量。对ＨＰＬＣ,ＣＺＥ,ＭＥＣＣ的分析条件作了一些选择实验,结果表明ＭＥＣＣ法与ＨＰＬＣ法分析数据接近、比较准确,而且前者比ＨＰＬＣ法分离效率高、溶剂用量少,是一种很有发展潜力的分析方法。     

Identification of a major new involatile N-nitroso compound in smoked bacon

The new N-nitroso compound identified in smoked bacon is 2-(hydroxymethyl)-3-nitrosothiazolidine-4-carboxylic acid. Identification was based on comparison of data from liquid chromatography, capillary gas chromatography and mass spectrometry with those for the authentic compound, the synthesis of which is described.     

Effect of electric field on liquid chromatographic separation of peptide digests. Combining capillary separation techniques

A system is described which allows operation of a range of capillary based liquid phase separations including capillary electrophoresis, isocratic and gradient capillary electrochromatography, isocratic and gradient capillary liquid chromatography and electrically assisted gradient capillary liquid chromatography. The system was coupled to electrospray ionization mass spectrometry in the electrically assisted capillary liquid chromatography mode to investigate the effect of applied voltage on the selectivity in peptide mapping separations. Analyses were performed on tryptic digests of recombinant human growth hormone and tissue plasminogen activator. The results show a small but useful effect on selectivity that can be used to fine tune specific separations.     

Determination of aromatic hydrocarbons in petroleum jet fuels by capillary gas chromatography and high-performance liquid chromatography

About a hundred hydrocarbon compounds have been identified as components of petroleum jet fuel by capillary gas chromatography and high-performance liquid chromatography. In gas chromatography stuides, glass capillary columns over 100 m long with polysiloxane OV-101 have been used as the stationary phase. In liquid chromatography, 150-mm-long columns with a separation ability of about 60 000 theoretical plates meter of length have been used to separate partitioned fractions of aromatic hydrocarbons from petroleum jet fuels of various origins.     

开管毛细管色谱柱的制备及其在蛋白质组学研究中的应用进展

近年来随着生命科学等领域的深入发展,人们对微量样本分离分析的需求越来越高,液相色谱系统的微量化受到了更多的关注。由于开管毛细管色谱柱具有较低的反向压力,可通过采用更长的色谱柱提高柱效,从而实现对复杂生物样本的高效分离,因而成为液相色谱柱新的发展方向。本文对开管毛细管色谱柱的制备方法及应用进展进行了综述。     

氨基酸的分析方法及其应用进展

从衍生试剂角度,介绍了不同衍生化氨基酸的分析方法,包括离子交换色谱法、高效液相色谱法、气相谱法和毛细管电泳法,以及无需衍生化的直接分析法高效阴离子交换色谱-积分脉冲安培法,并总结了蛋白质、食品和生理体液样品中的氨基酸分析方法。     

Comprehensive two-dimensional chromatography and capillary electrophoresis coupled with tandem time-of-flight mass spectrometry for high-speed proteome analysis

A comprehensive two-dimensional capillary liquid chromatography and capillary zone electrophoresis system coupled with tandem matrix assisted laser desorption/ionization-time of flight-time of flight-mass spectrometry (MALDI-TOF-TOF-MS) proteomics analyzer is presented. Protein/peptide samples were separated by capillary high-performance liquid chromatography (cHPLC). The effluents from cHPLC (the first dimension) were continuously transferred into capillary zone electrophoresis (CZE, the second dimension) through a novel valve-free hydrodynamic sampling interface. The CZE effluents were mixed with alpha-cyano-4-hydroxycinnamic acid (CHCA) matrix sheath flow via CE-MALDI interface, and then directly deposited on the MALDI target at a 3 s time-interval for further MS analysis. The high efficiency of the overall system was demonstrated by analysis of proteins in D20 (human hepatocellular carcinoma model in nude mice with high metastatic potential) liver cancer tissue. More than 300 proteins were identified, which proved the system potential for high-throughput analysis and application in proteomics.     

Overview of methods for the determination of trans fatty acids by gas chromatography, silver-ion thin-layer chromatography, silver-ion liquid chromatography, and gas chromatography/mass spectrometry

trans Isomers of naturally occurring cis-unsaturated fatty acids are produced when liquid vegetable oils or marine oils are partially hydrogenated to produce margarine, shortenings, and other hardened-fat products. Isomeric trans fatty acids are also formed in the intestinal tract of ruminants, and they appear in small amounts in dairy products and ruminant meat. Currently, satisfactory analyses for the fatty acid profiles of fats containing trans fatty acids are obtained by gas chromatography (GC) using capillary columns coated with highly polar cyanosilicone stationary phases. In capillary GC methods, the key limitation has been the incomplete separation of trans-monoenoic acid isomers from their cis isomers; however, recent reports have demonstrated that improvements in separation are attainable with the use of 100 m columns. In these columns, there is very little overlap of cis and trans isomers. More accurate trans fatty acid analyses can be obtained by coupling GC with either silver-nitrate thin-layer chromatography or silver-nitrate liquid chromatography.     

Chromatographic methods for petroleum fractions analysis

The state-of-the-art problem of the analysis of various petroleum fractions by the methods of high performance liquid and capillary gas chromatography, IR-spectroscopy, and mass-spectrometry has been considered. The core principle of high performance liquid chromatography as the principal method for petroleum fractions’ separation has been described. Some methods for the chemical modification of domestic silica have been presented. Methods for aromatic hydrocarbons in benzine, kerosene, and diesel petroleum fractions by the chromatography method have been described.     

Temperature‐programmed capillary high‐performance liquid chromatography with atmospheric pressure chemical ionization mass spectrometry for analysis of fatty acid methyl esters

A new capillary high‐performance liquid chromatography method with atmospheric pressure chemical ionization mass spectrometry was developed for the analysis of fatty acid methyl esters and long‐chain alcohols. The chromatographic separation was achieved using a Zorbax SB‐C18 HPLC column (0.3 × 150 mm, 3.5 μm) with a mobile phase composed of acetonitrile and formic acid and delivered isocratically at a flow rate of 10 μL/min. The column temperature was programmed simply, using a common column oven. Good reproducibility of the temperature profile and retention times were achieved. The temperature programming during the isocratic high‐performance liquid chromatography run had a similar effect as a solvent gradient; it reduced retention times of later eluting analytes and improved their detection limits. Two atmospheric pressure chemical ionization sources of the mass spectrometry detector were compared: an enclosed conventional ion source and an in‐house made ion source with a glass microchip nebulizer. The enclosed source provided better detectability of saturated fatty acid methyl esters and made it possible to determine the double bond positions using acetonitrile‐related adducts, while the open chip‐based source provided better analytical figures of merit for unsaturated fatty acid methyl esters. Temperature‐programmed capillary high‐performance liquid chromatography is a promising method for analyzing neutral lipids in lipidomics and other applications.     

Analysis of insecticidal proteins from Bacillus thuringiensis and recombinant Escherichia coli by capillary electrokinetic chromatography

Bacillus thuringiensis and recombinant Escherichia coli proteinaceous protoxins were subject to proteolysis and analyzed by capillary electrokinetic chromatography. Three resulting toxins (65 kDa) were baseline-resolved within 22 min using a 10 mM borate, pH 11 separation buffer consisting of 25 mM sodium dodecyl sulfate (SDS) and 30 mM phytic acid. The toxins displayed differential interactions with the SDS and phytic acid phases to effect their separation. The ion-pairing interaction between the analyte and phytic acid was also useful in preventing adsorption to the capillary walls and thus enhanced separation resolution and efficiency. The use of electrokinetic chromatography allows achievement of the separation in a significantly shorter time than conventional high-performance liquid chromatography (HPLC) using a diethylaminoethyl (DEAE) weak-anion exchanger.     

Chemical modification of analytes in speciation analysis by capillary electrophoresis, liquid chromatography and gas chromatography

Chemical modification of target analytes is widely used in modern analytical methods. This review focuses on the application of chemical modification techniques is the simultaneous analysis of metallic species by capillary electrophoresis, liquid chromatography and gas chromatography. Emphasis is placed on the procedures relating to analyses carried out by capillary electrophoresis. The development of this topic in the past five years is evaluated for liquid chromatography and gas chromatography. The advantages, performance and application in real samples are compared for the three techniques.     

Analytical tools for urocanic acid determination in human samples: A review

Urocanic acid is a chromophore found in the skin that has been identified as an important immunosuppressant and carcinogenesis mediator through its photoisomerization from trans to cis form induced by ultraviolet radiation. Research on analytical methods that explore urocanic acid isomerization is indispensable to fully understand the deleterious effects mediated by this biomarker. In this context, the current relevant analytical methods for determination of these isomers in human samples are summarized in this review. The methods presented here are applicable to human samples collected by noninvasive methods (or minimally invasive), encompassing an array of analytical techniques, including high‐performance capillary electrophoresis, confocal Raman spectroscopy, gas chromatography, high‐performance liquid chromatography, and mass spectrometry, among others. Developed high‐performance liquid chromatography methods have proven to be advantageous, allowing noninvasive collections for in vivo analysis and the confocal Raman, specially, for real‐time analysis. Among all these methods, high‐performance liquid chromatography is the most investigated one with mass spectrometry or ultraviolet detector, and the mass spectrometry detector being the most studied in the last years, demonstrating high sensitivity, very low detection limits, and accurate identification, especially for clinical investigations.     

Recent development of monolithic stationary phases with emphasis on microscale chromatographic separation

The column technologies play a crucial role in the development of new methods and technologies for the separation of biological samples containing hundreds to thousands compounds. This review focuses on the development of monolithic technology in micro-column formats for biological analysis, especially in capillary liquid chromatography, capillary electrochromatography and microfluidic devices in the past 5 years (2002-2007) since our last review in 2002 on monoliths for HPLC and CEC. The fabrication and functionalization of monoliths were summarized and discussed, with the aim of presenting how monolithic technology has been playing as an attractive tool for improving the power of existing chromatographic separation processes. This review consists of two parts: (i) the recent development in fabrication of monolithic stationary phases from direct synthesis to post-functionalization of the polymer- and silica-based monoliths tailoring the physical/chemical properties of porous monoliths; (ii) the application of monolithic stationary phases for one- and multi-dimensional capillary liquid chromatography, fast separation in capillary electro-driven chromatography, and microfluidic devices.     

Monitoring of cefepime in human serum and plasma by micellar electrokinetic capillary chromatography: Improvement of sample preparation and validation by liquid chromatography coupled to mass spectrometry

Cefepime monitoring in deproteinized human serum and plasma by micellar electrokinetic capillary chromatography and liquid chromatography coupled to mass spectrometry in presence of other drugs is reported. For micellar electrokinetic capillary chromatography, sample preparation comprised dodecylsulfate protein precipitation at pH 4.5 using an increased buffer concentration compared to that of a previous assay and removal of hydrophobic compounds with dichloromethane. This provided robust conditions for cefepime analysis in the presence of sulfamethoxazole and thus enabled its determination in samples of patients that receive cotrimoxazole. The liquid chromatography assay is based upon use of a column with a pentafluorophenyl‐propyl modified and multiendcapped stationary phase and the coupling to electrospray ionization with a single quadrupole detector. The performances of both assays with multilevel internal calibration were assessed with calibration and control samples and both assays were determined to be robust. Cefepime levels monitored by micellar electrokinetic capillary chromatography in samples from patients that were treated with cefepime only and with cefepime and cotrimoxazole were found to compare well with those obtained by liquid chromatography coupled to mass spectrometry. Cefepime drug levels determined by micellar electrokinetic capillary chromatography could thereby be validated.