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在反相和正相色谱模式下,研究了几种嘌呤衍生物在葫芦[6]脲单轮烷键合硅胶固定相上的高效液相色谱行为,并在反相模式下与ODS固定相进行了比较,考察了流动相中甲醇含量、流动相pH值和离子强度对嘌呤化合物保留的影响。研究结果表明:在反相模式下,嘌呤化合物与葫芦[6]脲单轮烷键合相之间存在多种相互作用,除疏水作用外,分离过程中还存在与ODS不同的色谱分离机制。在正相条件下,多作用力的色谱分离机制同样存在。葫芦[6]脲单轮烷键合相与溶质之间存在疏水、氢键、π-π和偶极-偶极等多种作用力,协同作用提高了固定相对嘌呤化合物的分离选择性。 相似文献
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采用嫁接法制备了一种新型高效液相色谱固定相.考察了固定相的液相色谱保留行为,发现该键合相具有很强的阴离子交换作用,还同时存在反相疏水作用.利用其疏水作用,可以对一些简单的有机化合物进行分离. 相似文献
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采用二维高效液相色谱-电喷雾质谱法,以新型色谱填料ClickCD为第一维分离材料,WatersXTerraMSC18柱作为第二维,以乙腈和0.2%甲酸-水为梯度洗脱流动相,对姜黄中的姜黄素类和倍半萜类化合物进行分离鉴定.结果表明,基于不同分离机理的ClickCD和C18二维色谱系统具有分离度高、正交性好的优点,使待测化合物得到了有效分离.特别是与高灵敏度的质谱联用,可以大大提高化合物的鉴定能力.通过与对照品的色谱保留时间和质谱数据对比,并结合文献报道,共鉴定了20个姜黄素类化合物和19个倍半萜类化合物,其中27个为对照品的同分异构体.为中药化合物的表征和活性化合物的制备提供了有效方法. 相似文献
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氮杂冠醚、环糊精混合功能基键合硅胶液相色谱固定相的合成与评价 总被引:2,自引:0,他引:2
冠醚键合固定相主要用于一些无机离子的分离,我们用连续固液相法合成了一系列冠醚键合硅胶固定相,并成功地用于有机化合物的分离[1~4];β-CD的内腔疏水而外缘亲水,可以选择性地包结含苯环及萘环的化合物,且具有手性拆分能力,已被用于手性色谱固定相[5,... 相似文献
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反相液相色谱(RPLC)是当前色谱分离中应用最为广泛的色谱模式,依靠疏水固定相与溶质之间的疏水相互作用实现弱极性和中等极性化合物的高效分离。但是,RPLC 对极性化合物(如寡糖、强极性寡肽、药物等) 的保留很弱,甚至不保留。反相离子对色谱(RPIC)、离子交换色谱(IEC)和正相色谱(NPLC)等可以作为RPLC 的补充,用于极性化合物的分离。然而,它们又各自存在一定的局限性,不能满足当前复杂样品的分离和表征需求。
亲水作用色谱(hydrophilic interaction liquid chromatography, HILIC)作为一种分离极性化合物的液相色谱模式,其概念最早由Alpert 于1990 年提出。HILIC 的主要特征是使用类似于NPLC 的极性固定相和水/有机溶剂(通常是乙腈)作为流动相,其中水是强洗脱溶剂。与NPLC 类似,在HILIC 模式下化合物的保留时间随其极性增强而增加。HILIC越来越受到关注和重视,一方面是因为强极性化合物的分离问题引起了各个研究领域的重视,包括药物分析、食品分析及蛋白质组学等领域都不同程度地涉及极性化合物的分离问题;另一方面是由于HILIC 具有其自身的优势。首先,HILIC 模式对强极性和亲水性化合物具有很好的保留和分离选择性,是解决各类强极性和亲水性化合物分离问题的可靠手段。其次,HILIC 模式使用的流动相体系相对简单,操作方便,而且克服了NPLC 的流动相溶解性差、保留时间对流动相中水含量十分敏感以及质谱兼容性差等问题。此外, HILIC的分离机理与RPLC 完全不同,两者的分离选择性有很好的正交性,适合用于构建HILIC-RPLC 二维色谱系统,是解决复杂样品分离问题的有效手段之一。近十年来,HILIC分离材料、分离原理和分离方法开发等领域均取得了巨大进展,在食品、药品、天然产物、蛋白质组以及代谢组学等分离分析中的应用日益广泛和成熟。 相似文献
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Hsieh Y Bryant MS Gruela G Brisson JM Korfmacher WA 《Rapid communications in mass spectrometry : RCM》2000,14(15):1384-1390
A sensitive, efficient, high throughput, direct injection bioanalytical method based on a single column and high-performance liquid chromatography (HPLC) with tandem mass spectrometry (MS/MS) was developed for pharmacokinetic analysis of early drug discovery compounds in plasma samples. After mixing with a working solution containing an internal standard each plasma sample was directly injected into a polymer-coated mixed-function column for sample cleanup, enrichment and chromatographic separation. The stationary phase incorporates hydrophilic polyoxyethylene groups and hydrophobic groups to the polymer-coated silica. This allows proteins and macromolecules to pass through the column due to restricted access to the surface of the packing while retaining the drug molecules on the bonded hydrophobic phase. The analytes retained in the column with a largely aqueous liquid mobile phase were then chemically separated by switching to a strong organic mobile phase. The column effluent was diverted from waste to the mass spectrometer for analyte detection. Within 200 plasma sample injections the response ratio (analyte vs. internal standard, %CV = 4.6) and the retention times for analyte and internal standard were found consistent and no column deterioration was observed. The recoveries of test compound in various plasma samples were greater than 90%. The total analysis time was =5 min per sample. 相似文献
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《Journal of separation science》2018,41(9):1973-1982
Analysis of N‐glycans released enzymatically from patients’ sera or other clinical samples may provide diagnostically and prognostically important information on human disease. Permethylation of these biomolecules simultaneously increases their hydrophobicity and substantially improves their detection parameters in the following mass spectrometric analyses. The overall procedure, from the glycan cleavage to the final mass spectrometric determinations, includes several steps involving extraction, derivatization, and purification. During these steps, certain polymeric contaminants that may have been coincidentally introduced could hamper the final measurements. To understand and counter these interferences and further fractionate or preconcentrate these glycans, we introduce here an effective microgradient chromatographic technique that employs a small reversed‐phase microcolumn connected to a gas‐tight microsyringe delivering a mobile‐phase gradient. After loading the glycan fraction onto the microcolumn, three elution steps are recommended: (1) remove polar contaminants; (2) recover permethylated glycans for either liquid chromatography with electrospray ionization mass spectrometry or matrix‐assisted laser desorption/ionization mass spectrometry; and (3) remove larger polymeric contaminants and regenerate the precolumn. We further demonstrate that the trapped second fraction can be beneficially preconcentrated and further separated to achieve matrix‐assisted laser desorption/ionization mass spectrometric detection of the derivatized N‐glycans up to 6300 Da. The enhanced detection capabilities for tetra‐antennary N‐glycans are of increasing interest in disease biomarker discovery. 相似文献
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Brandon L. Salazar Zoe Y. Marr Jason B. Benedict Luis A. Colón 《Journal of separation science》2023,46(10):2200830
Diarylethene-based photoswitches have become very popular over the last few decades for potential applications in chemistry, materials science, and biotechnology due to their unique physical and chemical properties. We report the isomeric separation of a diarylethene-based photoswitchable compound using high-performance liquid chromatography. The separated isomers were characterized by ultraviolet-visible spectroscopy and mass spectrometry confirmed the isomeric nature of the compounds. The isomers were purified by preparative high-performance liquid chromatography, providing fractionated samples to study the isomers individually. A total amount of 13 mg of an isomer of interest was fractionated from a solution of 0.4 mg/ml of the isomeric mixture. Because the preparative high-performance liquid chromatographic method required large quantities of solvent, we explored the use of supercritical fluid chromatography as an alternative separation mode which, to the best of our knowledge, is the first time this technique is used to separate diarylethene-based photoswitchable compounds. Supercritical fluid chromatography provided faster analysis times while maintaining sufficient baseline resolution for the separated compounds and consuming less organic solvent in the mobile phase compared to high-performance liquid chromatography. It is proposed that the supercritical fluid chromatographic method be upscaled and used in future fractionation of the diarylethene isomeric compounds, becoming a more environmentally benign approach for compound purification. 相似文献
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J. M. Bermúdez-Saldaña C. Quiñones-Torrelo S. Sagrado M. J. Medina-Hernández 《Chromatographia》2002,56(5-6):299-306
Summary Micellar liquid chromatography methods for quality control of pharmaceutical preparations (capsules, pills, tablets, injections)
containing the tricyclic antidepressants amineptine, amitriptiline, clomipramine, doxepin, imipramine, melitracen and nortriptyline
alone or together with other CNS drugs like diazepam, medazepam and perphenazine are described. The methods using micellar
solutions of cetyltrimethylammonium bromide as mobile phases and UV detection are rapid and reproducible. Due to the versatility
of interactions in micellar liquid chromatography, it is possible determine highly hydrophobic compounds such as TCAs in a
short time using mobile phases containing low organic solvent concentrations and usual flow rates, in contrast with the RP-HPLC
methods proposed for these compounds. Samples preparation only requires solution and adequate dilution with the mobile phase
before injection into the chromatographic system. 相似文献
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Summary Deuterated compounds have been used as mobile phases for microcolumn high-performance liquid chromatography (HPLC) employing flow-cell Fourier transform infrared spectroscopy for detection. Separations were carried out on adsorption, reversed-phase, non-aqueous size-exclusion and aqueous size-exclusion chromatographic columns. Due to the IR transparency of deuterated compounds in a C–H stretching region they represent nearly ideal eluents in terms of universal detection. In addition, due to the shift in the absorption wavenumber following deuteration, deuterated solvents allow FTIR detection of solutes in other regions, where otherwise it would be prohibited, or sensitivity sacrified by interfering solvent absorption. 相似文献
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Smith C Jensen BP Wilson ID Abou-Shakra F Crowther D 《Rapid communications in mass spectrometry : RCM》2004,18(13):1487-1492
High-performance liquid chromatography (HPLC) combined with inductively coupled plasma mass spectrometry (ICPMS) has been studied as a means for the detection of carbon to provide a 'universal' method for detecting organic compounds in chromatographic eluents. Carbon is particularly difficult to ionise and the amount of carbon present in normal chromatographic systems leads to high backgrounds, making detection a challenge. Novel separation approaches were therefore employed, using either entirely aqueous eluents (at temperatures of 60 and 160 degrees C, dependent on the column used) to eliminate the organic modifier completely, or isotopically enriched solvents. For the aqueous eluents, detection limits for sulphanilamide were found to be 2.26 microg, corresponding to 1.13 micromol (0.47 micromol of carbon), injected on a conventional 4.6 mm i.d. column. The use of a narrow bore column with highly isotopically enriched 12C-methanol (99.95 atom%) as organic modifier for the mobile phase enabled the detection of 86 micromol for 13C-triple-labelled caffeine and 79 micromol for 13C-double-labelled phenacetin. The sensitive detection of 12C-compounds with 13C-enriched methanol as organic modifier proved impractical due to a lower level of isotopic enrichment (99 atom%) of this solvent, with the residual 12C-methanol resulting in significant interference. 相似文献
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Microcolumn High-Performance Liquid Chromatography of ortho-Substituted Hydrophobic Phenol Derivatives 总被引:1,自引:0,他引:1
The influence of the structure of phenol derivatives with hydrophobic orthosubstituents on their retention in microcolumn normal-phase high-performance liquid chromatography was considered. The dependence of the retention parameters of ortho-substituted phenols on the total polarity of the mobile phase was analyzed. The revealed trends were taken into account in the optimization of the chromatographic separation of the above compounds. 相似文献
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Different nonvolatile mobile phases have been tested for the combination of ion-exchange chromatography combined with mass spectrometric detection of anions and organic acids. Buffer systems based on carbonate, sulfate, oxalate and citrate as the eluting species have been used. Among these, citrate proved to be the most versatile eluent allowing the separation of anions with absolute detection limits between 0.4 and 0.7 ng and of organic acids with detection limits between 0.4 and 4 ng in the non-suppressed mode. In the suppressed eluent mode iodate, bromate and chlorate could be separated using sodium carbonate as the mobile phase resulting in detection limits of 50 pg. The method was applied to the analysis of water samples containing oxyhalides originating from ozonization. Additionally, organic acids were separated by chromatographic separation techniques like reversed-phase, ion-pair or ion-exclusion chromatography and the compatibility with mass spectrometry was investigated with special respect to sensitivity of this detection mode. 相似文献
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Valleix A Carrat S Caussignac C Léonce E Tchapla A 《Journal of chromatography. A》2006,1116(1-2):109-126
The separation of solutes that differ only in the extent of isotopic substitution of their hydrogen atoms, using either mixtures of isotopically non-modified or perdeuterated solvents as mobile phases, is described. The occurrence of a secondary isotope effect is demonstrated in reversed-phase liquid chromatography, which is independent of the nature of the stationary phase (different octadecyl-bonded silicas, an embedded alkylamide-bonded silica, as well as one polymeric stationary phase were tested), and the water content and the nature of organic modifier of the mobile phase. The separation of 24 structurally different isotopologue pairs (apolar compounds and polar compounds with exchangeable or non-exchangeable hydrogen atoms) is examined using reversed-phase liquid chromatography. It is found that the greater the number of isotopically substituted hydrogen atoms in a given organic solute, the better is the separation of a particular isotopologue pair. The single secondary isotope effect is shown to be dependent on the number of isotopic substitutions. The greater the number of these substitutions, the smaller is the single isotope effect. The single secondary isotope effect is higher for aromatic hydrocarbons than for aliphatic hydrocarbons. A secondary isotope effect is also observed in chiral chromatography and normal-phase liquid chromatography, as well as on changing the nature of the substituting isotope, i.e.: tritium instead of deuterium. Thus, we have demonstrated that the total secondary isotopic effect for hydrogen/tritium is higher than for hydrogen/deuterium. This isotope effect involves only the consequences of changes in interactions due to nuclear motions. Overall this study confirms the predominance of hydrophobic effects in retention processes in reversed-phase liquid chromatography. In reversed-phase liquid chromatography, a secondary isotope effect related to mobile phase composition is also observed. The behaviour of deuterium oxide and water in mobile phases of the same composition (%, w/w) is compared. Independent of the nature of the organic modifier (methanol, acetonitrile or ethanol), the effect of replacing H2O with 2H2O in the mobile phase, is an increase in the retention factors and an improvement in the chromatographic resolution of isotopologue pairs. This increase in the resolution is not accompanied by a change in the chromatographic selectivity. The measurement of liquid-liquid extraction coefficients proves that the effect is mainly due to the modification of the phase ratio. In general the effect of 2H-labelled solvents (2H2O and C2H3CN) as mobile phase components, compared to their isotopically non-modified isomers, can be rationalized on the basis of their lower polarisabilities. Overall the use of perdeuterated rather than isotopically non-modified solvents as mobile phase components leads to the most efficient separation systems. 相似文献
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Cyanobiphenyl-mesogened liquid crystalline polymer is bonded on silica by surface-initiated atom transfer radical polymerization and is used as the stationary phase for liquid chromatography. Various instrumental analyses such as elemental analysis, X-ray photoelectron spectroscopy and differential scanning calorimetry were used for its characterization. The stationary phase exhibits multiple characteristics of low hydrophobicity, low hydrophobic selectivity, polarity recognition and shape selectivity in the separation of polyaromatic hydrocarbons and polar neural aromatic compounds. Temperature and mobile phase composition were confirmed to have effects on the chromatographic behavior. Isomers of polyaromatic hydrocarbons and carotenes are well separated on the stationary phase. 相似文献