一种新型液相色谱屏蔽键合相的色谱性能

烷基硅胶键合固定相 ,特别是十八烷基键合固定相 ,是应用最广泛的反相色谱固定相 ,改变流动相组成 ,就可实现大多数有机化合物的分离分析 .但是 ,由于硅胶表面残留硅醇基的存在 ,分离某些极性化合物 ,特别是碱性有机化合物时使色谱峰变形拖尾 ,灵敏度下降 .采用封端技术也不能完全消除残留硅醇基的影响 .在分离碱性物质时大都采用缓冲溶液流动相 ,长期使用缓冲溶液将影响仪器和色谱柱的性能和寿命 .近年来 ,为了改善碱性化合物的分离 ,提出了空间保护相 [1] 和烷基酰胺屏蔽相 [2 ,3] .依据静电屏蔽原理 ,我们 [4 ]曾制备了十四烷基胺反相色…     

对-叔丁基杯[8]芳烃键合硅胶制备及其毛细管电色谱性能研究

以γ-(环氧丙氧)丙基键合硅胶为前体,于硅胶表面键合环氧基,在催化剂存在下以杯芳烃钠盐开环制备杯芳烃键合硅胶固定相.该方法反应条件温和,适用性强.将这个新方法首次用于制备对-叔丁基杯[8]芳烃电色谱键合固定相(C8BS),采用加压电色谱初步评价其电色谱性能.研究结果表明,C8BS电渗流(Electrosmoticflow,EOF)较小,但通过控制键合反应及使用压力辅助电色谱可部分弥补上述不足.该固定相的EOF受流动相pH影响小(pH=3-8),同时大环配体屏蔽效应能有效地克服硅羟基引起的碱性化合物拖尾现象,这对电色谱分离具有重要意义.通过分步封尾研究EOF的来源发现,杯芳烃酚羟基对EOF有弱的贡献,这与报道的杯芳烃涂层具有径向电渗流调控能力相一致.     

用于碱性物质分离的高效液相色谱键合相的制备及评价

采用２,４－戊二酮与正辛烷基二甲基氯硅烷反应制成活泼的中间体——硅醚型硅烷中间体,然后再与硅胶进行键合。经元素分析、漫反射红外光谱和高效液相色谱法对键合相进行了鉴定和评价。结果表明,键合反应按预定路线进行,硅胶表面被键合相基团覆盖的较均匀、完全。键合相具有较好的色谱性能,可有效地用于碱性化合物的分离分析中。     

浸渍法制备C_(18)反相高效液相色谱固定相

提出了一种浸渍法制备C_(18)高效液相色谱固定相的方法。以十八烷二甲基氯硅烷(ODC)为键合试剂、六甲基二硅氮烷(HMDS)为封尾试剂,通过浸渍法制备得到C_(18)高效液相色谱固定相。采用红外光谱(FTIR)、元素分析(EA)和氮气吸附与解吸附(BET)对该合成材料进行了表征,并通过SRM870评价体系对其疏水选择性、金属离子以及硅羟基活性进行评价。与商品柱Kromasil C_(18)相比,浸渍法制备的C_(18)固定相具有较少的金属离子活性及较低的硅羟基残余量。通过重复性考察,说明浸渍法制备的C_(18)柱键合层稳定,对溶质的保留重现性良好。     

厚朴酚键合硅胶高效液相色谱固定相分离嘌呤、嘧啶、蝶呤及黄酮

将新制备的厚朴酚键合硅胶固定相(MSP)用于嘌呤、嘧啶、蝶呤及黄酮类化合物的液相色谱分离分析。选取了4种嘌呤、8种嘧啶、4种蝶呤及5种黄酮类药物作为极性化合物的代表,以商品反相碳十八烷基键合硅胶柱(ODS)作参照,研究了新固定相对碱性化合物的选择性和相关分离机理。实验发现,在简单流动相条件下,厚朴酚键合硅胶固定相对上述药物表现出较高的选择性及分离效果。尽管MSP没有进行封尾处理,但含氮类极性化合物(嘌呤、嘧啶、蝶呤)仍表现出基本对称的色谱峰形。多数药物在两柱上的洗脱顺序大致相同,说明疏水作用始终存在,这说明新固定相具有反相色谱性能。比较研究还发现,MSP在分离上述极性药物时能够提供除疏水性作用之外的其他作用位点。例如,在分离嘌呤、嘧啶及蝶呤时,氢键和偶极作用明显存在;同时MSP与溶质结构中的芳环(硫唑嘌呤、紫花牡荆素)之间有较强的π-π电子相互作用等,使得含氮类极性化合物和黄酮的保留一般比ODS强,分离度也有一定的改善。多种作用可以合理地解释MSP柱对极性溶质有更强的分离能力,厚朴酚键合硅胶固定相可在一定程度上弥补ODS单一疏水作用的不足,有利于分类碱性化合物。     

混合型烷基键合硅胶液相色谱固定相的合成与性能评价

多环芳烃;取代基位置异构体;混合型烷基键合硅胶液相色谱固定相的合成与性能评价     

生物碱在十八烷基膦酸改性锆-镁复合氧化物固定相上的色谱行为

研究了某些生物碱在十八烷基膦酸改性锆-镁复合氧化物固定相(C18PZM)上的色谱行为。通过考察流动相参数如甲醇含量、缓冲液pH值和离子强度对生物碱保留的影响,对这类化合物在该固定相上的保留机理进行了探讨。结果表明,在实验色谱条件下,生物碱在C18PZM上表现出反相和阳离子交换的混合保留模式机理。锆-镁基质上化学吸附的十八烷基膦酸和其对流动相中路易斯碱的吸附以及锆羟基本身均有可能是该固定相的离子交换作用位点的来源。高pH值流动相,溶质大部分以分子状态使用形式存在,因此其保留以疏水作用为主。在甲醇-pH 10.1 Tris缓冲液,生物碱的分离取得了满意的结果。与传统的烷基键合硅胶反相固定相相比,C18PZM表现出了更优越的化学稳定性,对于碱性化合物,尤其是具有高pKa值的碱性化合物的分离分析有着广泛的应用前景,有望发展为与硅胶键合固定相互补的一类反相HPLC的固定相。     

金属有机化合物的分析(Ⅵ)——极性与非极性二茂铁化合物的高效液相色谱研究

本文以国产YWG-C_(18)H_(37)(十八烷基键合微粒硅胶)为固定相,以不同比例的甲醇-水为流动相进行二茂铁化合物的反相高效液相色谱研究,分离了十一类共32种不同极性的二茂铁化合物,并探讨了它们在反相色谱中保留特性和分子结构的关系。     

十四烷基胺键合固定相的反相色谱性能

制备了一种新型反相液相色谱固定相──十四烷基胺硅胶键合固定相。以甲醇和水为二元流动相,评价了该固定相的疏水性、选择性和残留硅醇基活性。同时分离了包括碱性、酸性和中性有机化合物在内的混合物。结果表明,在该固定相上,碱性化合物的色谱峰对称性较好,硅酸基活性受到抑制,并具有良好的选择性。     

厚朴酚键合硅胶液相色谱固定相的制备、表征与性能评价

通过γ-巯丙基三甲氧基硅烷(KH-590)的作用, 将具有抗菌功能的中草药厚朴的主要药用成分厚朴酚键合在硅胶表面上, 制备了厚朴酚键合硅胶液相色谱固定相. 采用红外光谱、元素分析和热重分析对该固定相进行了表征. 以苯同系物、5种吡啶、6种苯胺和8种芳香羧酸类化合物为溶质探针, 初步考察了该新型固定相的基本色谱性能, 研究了其对这些化合物的保留机理. 结果表明, 该固定相的反相色谱性能类似于十八烷基键合硅胶固定相(ODS), 分离原理与疏水性作用有关; 另外, 该固定相包含有别于疏水性作用的氢键作用、π-π电荷转移作用和偶极-偶极等作用, 多种作用力使其在分离某些可电离的碱性和酸性化合物时表现出更好的选择性和分离效果. 厚朴酚配体的多种作用位点对快速分离极性芳香化合物有重要贡献.     

Analysis of basic compounds at high pH values by reversed-phase liquid chromatography

Reversed phase high performance liquid chromatography (RPLC) is currently the method of choice for the analysis of basic compounds. However, with traditional silica materials, secondary interactions between the analyte and residual silanols produce peak tailing which can negatively affect resolution, sensitivity, and reproducibility. In order to reduce these secondary interactions, which comprise ion exchange, hydrogen bonding, and London forces interactions, chromatographic analyses can be carried out at low or high pH values where silanol groups and basic compounds are mostly uncharged. The chromatographic behaviour of a particular bidentate stationary phase, Zorbax Extend C18, was studied with a set of basic and neutral compounds. Thanks to a higher chemical stability than traditional silica based supports, analyses were carried out with a high pH mobile phase, which represents a good alternative to the acidic mobile phases generally used to reduce ion exchange interactions. The performance of this bidentate stationary phase was also compared with that of other supports and it was proved that it is advantageous to work with high pH mobile phases when analyzing basic compounds.     

Preparation and characterization of a new p-tert-butyl-calix[8]arene-bonded stationary phase for high-performance liquid chromatography.

A new p-tert-butyl-calix[8]arene-bonded silica gel stationary phase (CABS) was prepared via 3-glycidoxypropyltrimethoxysilane as a coupling reagent for HPLC. Its structure was characterized by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), elemental analysis and thermal analysis. The chromatographic performance of new packing was evaluated by using basic, acidic and neutral aromatic compounds as probes compared with conventional ODS. The results show that the new stationary phase has an excellent reversed-phase property and high selectivities for substituted aromatics compared with ODS, because CABS can provide various sites for the analytes, such as hydrogen-bonding interactions, pi-pi interactions, and inclusion complex, besides hydrophobic interactions.     

A study of the behaviour of some new column materials in the chromatographic analysis of Cinchona alkaloids

Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing materials specially designed for the separation of basic compounds has been studied using mobile phases without the special additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied. The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silica-based C₁₈ material proved superior to the polymer materials tested.     

A study of the behaviour of some new column materials in the chromatographic analysis of Cinchona alkaloids

Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing materials specially designed for the separation of basic compounds has been studied using mobile phases without the special additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied. The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silicabased C₁₈ material proved superior to the polymer materials tested.     

Rapid Screening of Volatile Ion-Pair Reagents Using UHPLC and Robust Analytical Method Development Using DoE for an Acetyl Cholinesterase Inhibitor: Galantamine HBr

As over 70% of pharmaceutical compounds are bases, the analysis of these basic compounds by high performance liquid chromatography (HPLC) continues to be of great value and interesting. Acetyl cholinesterase inhibitors (AChEIs), which contain the basic compounds like Rivastigmine tartrate, Galantamine hydrobromide and Donepezil with different polarities, were chosen for the study. A rapid screening of the volatile ion-pairing reagents was performed using modern techniques like ultra high performance liquid chromatography (UHPLC). The experiments were planned using the ??Design of Experiments?? (DoE) approach to identify the LC?CMS compatible ion-pair reagent. In this study, Heptafluorobutyric acid (HFBA) has given a very good peak shape with tailing factor at 1.4 and theoretical plates up to ~5,000 were observed, compared to tailing factor at 1.9 and theoretical plates up to ~3,000 with non-volatile ion-pair reagent sodium heptane sulphonate (SHS). Similarly retention with HFBA was optimum as ~5 min in short run time method compared to ~13 min with SHS. This ion-pair reagent has proved to be good replacement of sodium alkyl sulphonate modifiers. HFBA can also be used for semi-preparative work for isolation of impurities by just evaporating the solvents. It avoids the extraction of other inorganic modifiers.     

Ultrafast UPLC‐ESI‐MS and HPLC with monolithic column for determination of principal flavor compounds in vanilla pods

In this study, two novel chromatographic methods based on monolithic column high‐performance liquid chromatography (HPLC) and ultra‐performance liquid chromatography (UPLC) were developed for the ultrafast determination of principal flavor compounds namely vanillin, vanillic acid, p‐hydroxybenzoic acid, and p‐hydroxybenzaldehyde in ethanolic extracts of Vanilla planifolia pods. Good separation was achieved within 2.5 min using Chromolith RP18e column (100 mm×4.6 mm) for HPLC and Acquity BEH C‐18 (100 mm×2.1 mm, 1.7 μm) column for UPLC. Both methods were compared in terms of total analysis time, mobile phase consumption, sensitivity, and validation parameters like precision, accuracy, LOD, and LOQ. Further, system suitability test data including resolution, capacity factor, theoretical plates, and tailing factor was determined for both the methods by ten replicate injections. Monolithic column based HPLC gave better results for most of the selected parameters while UPLC was found to be more eco‐friendly with low mobile phase consumption and better sensitivity. Both methods may be used conveniently for the high throughput analysis of large number of samples in comparison to traditional particulate column.     

生物碱的高效液相色谱分离分析与纯化制备研究进展

生物碱是天然产物中药用活性较好的一类化合物,在分离科学与技术领域,生物碱的分离一直是一个研究热点和难点问题。近年来,随着高效液相色谱填料和分离方法的发展,生物碱的分离分析和纯化制备有了长足的进步。该文主要针对碱性化合物的峰形拖尾问题,综述了高效液相色谱理论的发展和色谱分离技术的进步,以及近年来新型色谱填料和分离方法在生物碱分离分析和纯化制备中的应用,并对其前景进行了展望。     

Chemically bonded phases for the reversed-phase high-performance liquid chromatographic separation of basic substances

A chemically bonded phase with a peptide group (PB) for reversed-phase high-performance liquid chromatography (HPLC) is described. This packing was prepared by a two-stage modification of the surface of silica gel with mono- and trifunctional 3-aminopropylsilane and then with an appropriate derivative of a fatty acid. Packings prepared in this way were compared with standard C18 materials used in HPLC. Surface characteristics of the packings before and after chemical modification were determined by different physico-chemical methods, e.g., porosimetry, elemental analysis, 13C and 29Si cross-polarization magic angle spinning NMR and HPLC. Chromatographic properties of these packings were evaluated by comparison between log k' of one phase and log k' of a second phase for substances with different chemical natures. The PB packing was found to be especially useful for the separation of basic substances.     

姜黄素键合硅胶固定相的制备、表征及色谱性能

通过γ-［(2,3)-环氧丙氧］丙基三甲氧基硅烷(KH-560)偶联剂将具有抗菌功能的植物有效成分姜黄素键合到硅胶上,制备了姜黄素液相色谱键合硅胶固定相(CCSP)。采用元素分析、红外光谱和热分析对该固定相结构进行了表征。以甲醇和水为二元流动相,不同的中性、酸性和碱性化合物为溶质探针,并用ODS柱作参比,对固定相的色谱性能及保留机理进行了研究。研究结果表明,姜黄素键合固定相不仅具有良好的反相色谱性能,同时由于配体结构中所含有的基团形成了含芳环的共轭体系,从而引入了n-π和π-π作用位点,所含的羟基和β-二羰基与溶质之间存在偶极-偶极和氢键作用,与ODS相比,该固定相在极性化合物分离中占优势,且分析速度较快。     

Comparison of Micellar and Reversed-Phase Liquid Chromatography for Determination of Sulfamethoxazole and Trimethoprim

A simple, sensitive, and precise micellar liquid chromatographic method for simultaneous analysis of sulfamethoxazole and trimethoprim, with ultraviolet detection at 245 nm, has been developed, validated, and used for determination of the compounds in commercial pharmaceutical products. The compounds were well separated on a Hypersil ODS reversed-phase column at 35°C by use of a mobile phase consisting of 0.1M sodium dodecyl sulfate in a 2:98 (V/V) mixture of 1-butanol and pH 3.0 phosphate buffer solution at a flow rate of 1.0 mL min^?1. A comparative study of the performance of reversed-phase liquid chromatography with aqueous-organic or micellar-organic mobile phases for separation of sulfamethoxazole and trimethoprim is reported. The study showed that micellar liquid chromatography (MLC) and reversed-phase liquid chromatography (RP HPLC) are of similar efficiency, sensitivity, and selectivity for determination of sulfamethoxazole and trimethoprim.