Ion Exchange High Performance Liquid Chromatography of Leukotrienes

Abstract

A novel anion exchange liquid chromatographic system has been developed for isocratic separation of leukotrienes. Hydrophobic as well as ionic forces were found to influence the separation. By optimization of solvent strenght, ionic strenght and pH, amphoteric peptidoleukotrienes could be separated simultaneously with hydroxy fatty acids such as leukotriene B₄ and its ω-oxidized metabolites. To obtain a good buffering capacity of the mobile phase at optimum pH, a multicomponent buffer was developed.     

Liquid Crystals as Stationary Phases for High Performance Liquid Chromatography

Abstract

Liquid crystals have not yet been used as stationary phases in High Performance Liquid Chromatography. This is surprising since Gas Chromatography has demonstrated some remarkable separations, many of which are not possible with normal stationary phases, that have been achieved where liquid crystals have been employed as the stationary phase. The objective of the work reported here was to evaluate the chromatographic properties of several cholesteric liquid crystals as stationary phases in HPLC. Included in this study was an investigation of the feasibility of bonding a cholesteric moiety to a solid support for use in HPLC. The columns showed a dramatic increase in capacity factor for steroid molecules as the temperature of the column was increased.     

Determination of Cytokinins by Ion Suppression-Reverse Phase High Performance Liquid Chromatography

Abstract

A method for the separation of cytokinins has been developed by the use of ion suppression-reverse phase high performance liquid chromatography (IS-RP HPLC) with high efficiency, specificity and low sensitivity. Four reverse phase chromatographic columns were compared for their ability to separate and quantify six cytokinins with respect to signal response, resolution (R_S), capacity factor (k¹) and efficiency, N (number of theoretical plates). The optimal aqueous and organic phase components for the resolution of these cytokinins were determined with respect to pH, ionic strength and the proportion of the organic solvents, methanol and acetonitrile. Heptane sulfonic acid was used as an organic modifier. The optimal HPLC operating conditions were applied to separate and quantify the cytokinins present in a culture supernatant of Azotobacter chroococcum.     

Determination of Ampicillin in Plasma by Paired Ion High Performance Liquid Chromatography

Abstract

A new, accurate, precise, and specific method has been developed for the assay of ampicillin in plasma. No extraction of ampicillin from plasma is called for. Plasma is treated with acetonitrile containing propiophenone as the internal standard, vortexed, centrifuged, and the supernate is injected. A C18 reverse phase column is used. The mobile phase consisted of a mixture of methanol and 0.02M phosphate buffer of pH 6.00, and contained alkyldimethylamine C10 as an ion pair ligand. Detection was by UV at 220 nm. A linear relationship between concentration and peak area ratio was obtained. Recovery, day-to-day, and within-day variation were determined.     

Reverse Phase Ion Pair High Performance Liquid Chromatography of Viral Tryptic Glycopeptides

Abstract

Tryptic glycopeptides from influenza A/WSN (H₀N₁) and mink cell focus (MCF)-inducing (MCF-247) murine leukemía virus were subjected to high performance liquid chromatography (hplc) for mapping purposes. Hydrophilic ion-pairing was accomplished using 0.1% phosphoric acid on C₁₈ μBondapack and LiChrosorb RP-18 ODS commercially available columns. The samples were eluted from the column with acetonitrile with sample recovery in the range of 70 to 80%. The advantages of hplc over the conventional techniques previously used are detailed.     

蛋白质制备色谱的研究

研究了蛋白质纯化制备的二种运行模式,其一,在色谱柱超载下纯化制备蛋白质模式,并成功地用离子交换色谱纯化制备了大豆中的胰蛋白酶,用反相液相色谱纯化了细胞色素Ｃ;其二,用溶质－溶质顶替色谱纯化制备了核糖核酸酶－Ａ,并对顶替色谱过程中诸参数进行了讨论和选择。     

分子印迹液相色谱整体柱

分子印迹是合成预定选择性固定相的新兴技术,整体柱是新型的色谱固定相技术。将分子印迹聚合物与整体柱技术相结合,可以有效提高液相色谱的分离效率,有助于推动整个分离科学的发展,意义重大,是当今分析化学的研究热点。本文就分子印迹液相色谱整体柱的制备合成、色谱分离条件以及物理化学特性评价方法等方面的研究进展进行了较系统的综述,并对该技术目前存在的问题和发展前景进行了探讨。     

高效液相色谱整体柱技术的进展

高效液相色谱整体柱（又名连续床）具有制备相对简单、原料易得以及聚合组分在一定范围内可调节的优点,是近年来得到迅速发展的新型色谱柱。本文综述了目前高效液相色谱（HPLC）制备整体柱的典型高聚物体系、制备各种整体柱时反应条件的影响,并简要介绍了它的表征方法和应用。     

Sample Solvent as Analyte in High Performance Liquid Chromatography

Abstract

Solvents vary in their behavior in high performance liquid chromatography (HPLC). Water and methanol, among others, are widely used in the mobile phase as well as solvents for the solute. Few reports indicate that the solvent used for the solute can behave as an analyte. Normally, it is generally accepted that the solute solvent, a non-constituent of the mobile phase will be the first eluent. However, a solvent which is a component of the sample can show up as an unexpected peak with its own identity. This solvent may show a similar retention time as some of the unknown components of the sample. This indicates that in some cases the quantitative results may be the sum of the absorptivity of the solute and solvent used for the sample. It is assumed that some solvents show no absorption in the ultraviolet region at which the analysis is being conducted. Depending on the mobile phase composition some solvents can be detected at the wavelengts or wavelengths used for analysis. Water, ethylacetate, and methanol showed absorption at 210 nm when present in the sample being analyzed with a mobile phase of acetonitrile-methanol using a C₁₈ column. These solvents overlapped or showed retention times the same as estriol and testosterone.     

High Performance Liquid Chromatography of Dithiolthiones

Abstract

Sixteen dithiolthiones including oltipraz (5-(2-Pyrazinyl)-4-methyl-1-1, 2 dithiol-3-thione) and anethol dithiolthione (P-methoxyphenyl-1,2-dithiol-3-thione) have been studied using an isocratic high performance liquid chromatographic system. The retention characteristics of these compounds were determined using a conventional C 18 reverse phase column and a μ Bondapack phenyl column. The mobile phases used consisted of several concentrations of methanol and water. All compounds studied were adequately detected in the nanogram range (30–100 ng on column) using ultra violet detection (UV) set at 300 nm. Several analogs and isomers were separated. The retention characteristics of the 16 compounds studied are reported for both columns using 4 mobile phases and chromatograms of reference standards are presented.     

Preparation of High Efficiency Columns for High Performance Liquid Chromatography

Abstract

This method employs a specially constructed slurry reservoir, which features an internal taper and a quick-disconnect pump fitting. A major innovation is the use of a three-solvent system to maintain a slurry of packing material as a ‘slug’ within the reservoir. A measured amount of carbon tetrachloride is poured into the empty reservoir-column assembly. The column packing material is introduced as an isopropanol slurry and the reservoir is filled with isooctane. The assembly is then connected to a Haskel DSTV 122C pump, and the column is packed with isooctane at 10,000 psi pressure.

This procedure provides HPLC columns with efficiencies of 40,000 plates per meter for 10-micron silica, 30,000 plates per meter for 10-micron C₁₈, and 70,000 plates per meter for 5-micron C₁₈ packing materials. We have used this method for preparation of over 35 HPLC columns during the past two years.     

Ethylammonium Acetate as a Mobile Phase Modifier for Reversed Phase Liquid Chromatography

We have synthesized the low melting hygroscopic ionic liquid ethylammonium acetate (EAA) and characterized a concentrated solution of EAA as a reversed phase mobile phase replacement for organic solvents like methanol. This solution of EAA acts like an organic solvent with a polarity parameter (P=6.0) similar to methanol (P=5.1) but less than water (P=10.2). A test mixture of salicylate, nitrofurantoin, and acetophenone was separated in this order on C1, C4, and C18 columns using an EAA modified aqueous mobile phase. On a C-18 column, the reduction in retention factor for acetophenone from about 20 to 2 as the % EAA is raised from 20–80% is similar to the same trend found using methanol. However, the retention order using methanol is first nitrofurantoin, then salicylate, and finally acetophenone. Log retention factor (k) versus the volume fraction of either EAA or methanol plots were linear indicating the solvent strength parameter for EAA was about 85% of that for methanol. Despite the relatively high viscosity of EAA, plate count values averaged only about 15% less for EAA as compared to methanol using the same mobile phase composition and could be raised by either working at a temperature above ambient or reducing the flow rate. EAA as a modifier allowed for faster separations of water-soluble vitamins on a reversed phase column designed for totally 100% aqueous mobile phases.Acknowledgements This work was supported by a grant from the Miami University Committee on Faculty Research. We thank ES Industries for the gift of the AquaSep column.     

Non-Porous Silica Supports for High Performance Liquid Chromatography

Abstract

The physical and chromatographic properties of two types of non-porous HPLC support materials were examined. Loading capacities of non-porous supports were about 10 fold less than of wide-pore gels, while their physical strength was much greater, suggesting that non-porous supports could be useful for polymer separations. Such materials appeared to be less suitable for low-molecular-weight solutes, except for fundamental retention studies, where the absence of pore structure offers a less ambiguous support matrix.     

Determination of Atenolol and Its Related Compounds by Ion Pair High Performance Liquid Chromatography

Abstract

A rapid, simple, accurate, and stability-indicating ion pair high performance liquid chromatography (IP HPLC) procedure is presented for the determination of atenolol in pharmaceutical tablets. The related compounds of atenolol were separated, making the determination specific for atenolol. An aliquot of the sample is dissolved in methanol containing N-butyryl-4-aminophenol as an internal standard and chromatographed on a supelcosil LC-8-DB (5μ) (25Omm × 4.6mm i.d.) column using 1.0 mM ammonium acetate and 2.0 mM octanesulfonic acid sodium salt in acetonitrile: water (25:75) solution adjusted to pH 3.5 with glacial acetic acid as the mobile phase. The detection was carried at 225 nm. The relative standard deviations are less than 1.0% for the two commercial products analyzed. The method was tested for linearity, recovery, and specificity.     

Separation of Deoxyribonucleotides Using Ion Suppression High Performance Liquid Chromatography with a Reversed-Phase Column

Abstract

Ion suppression-reversed phase high performance liquid chromatography, using 0.6 M ammonium dihydrogen phosphate as eluent, produces base-line separations of deoxyribonucleotides. The effects of pH and ionic strength are described. This isochratic system is simple, reproducible and fast, requiring less than 30 min for a complete separation, and is suitable for in vitro studies.     

荧光标记寡核苷酸的反相离子对色谱分析

建立荧光标记寡核苷酸反相离子对色谱分析方法,优化了流动相醋酸三乙胺浓度(0～0.15 mol/L), pH 4.5～7.0和洗脱强度等色谱条件.对5-mer, 10-mer和15-mer非标记和5'-羧基荧光素(5'FAM)标记寡核苷酸的保留进行比较分析,研究荧光标记寡核苷酸的保留机理,并分离TaqMan~(TM)探针等多种常用荧光标记寡核苷酸.结果显示,不同长度荧光标记寡核苷酸在0.01 mol/L醋酸三乙胺,pH 7.0的条件下获得最大分离.荧光标记寡核苷酸的保留与非标记寡核苷酸有明显差异,两者可完全分离.在一定长度范围内非标记寡核苷酸随长度的增加,保留时间增长;相反,荧光标记寡核苷酸的长度增加,保留时间减短.荧光染料疏水性对其标记的寡核苷酸在反相柱中的保留有较大影响,荧光染料疏水性越强,其标记寡核苷酸保留时间越长.但疏水性的影响程度随标记寡核苷酸长度增加而逐渐变小.     

Lewis碱改性氧化锆基质色谱固定相的研究进展

综述了Lewis碱改性氧化锆(或其复合氧化物)基质高效液相色谱填料的研究进展,涉及的改性剂包括氟离子、磷酸盐、有机膦酸、羧酸、酚类化合物、蛋白质和环糊精衍生物等。简要介绍了Lewis碱改性氧化锆固定相在毛细管电色谱中的应用。 引用文献51篇。     

High Performance Liquid Chromatography of Cholesteryl Esters

Abstract

The separation of cholesteryl esters by high performance liquid chromatography was facilitated by cooling of the column, followed by spontaneous return to ambient conditions. the resolution of the esters was increased. the method was applied to detection of the cholesteryl esters in plasma.     

氧化锆填料的高效液相色谱性能评价

研究了采用溶胶－凝胶技术制备的４－６μｍ粒径氧化锆微球的晶体结构,比表面积,孔容,孔径分布及表面酸碱性,测得氧化锆以单斜相和四方相２种相存在。微球的比表面积为２１ｍ６２／ｇ;总孔容为０．１２８０ｃｍ＾３／Ｌ;平均孔直径为８．６ｎｍ。氧化锆的表面存在酸碱两性。分别以异丙醇／环己烷,二氧甲烷／环己烷及三氯甲烷／环己烷为流动相研究了苯酚衍生物,芳香烃衍生物及苯胺等碱性化合物的保留行为。     

High Performance Liquid Chromatography of Uroporphyrin Isomers

Abstract

The separation of uroporphyrin I and III isomers by reversed-phase high performance liquid chromatography on ODS-Hypersil with ammonium acetate buffer-acetonitrile solvent systems is described. The effects of buffer concentration, pH, organic modifier proportion and different organic modifiers on the resolution are studied. The optimum conditions for the separation were 12–13% acetonitrile in 1M ammonium acetate buffer pH 5.10–5.20. The method also separated uroporphyrin I and III from the II isomers but the resolution of uroporphyrin III and IV isomers was not achieved.