Polysiloxane-encapsulated stationary phase for reversed-phase high-performance liquid chromatography

Summary Silica beads of 6-μm average diameter were silanized with methylvinyldiethoxysilane and then subjected to encapsulation with poly(methylvinylsiloxane). The resulting product is a new stationary phase for reversed-phase high performance liquid chromatography (RP-HPLC) which has superior ability for the separation of polar, non-polar and basic compounds. The chromatographic peaks are symmetric. Its stability has been studied; after continuous use for three months the carbon content and chromatographic behaviour of the phase were unchanged. on to the silica surface to given an uniform organic film. Material prepared in this way has both good chromatographic behaviour and superior selectivity. Because contact of the silica matrix with the mobile phase is avoided, the alkali-resisting ability of the stationary phase is increased. The non-specific adsorption of alkaline solutes on to the silica surface is also avoided because of the complete coverage of surface silanol groups. Reports of stationary phases encapsulated with polystyrene [6], polybutadiene [I] and octadecylsiloxane polymers have recently appeared in the literature [3]. In this paper we report the encapsulation of poly-(methylvinylsiloxane) (analogous to the phase SE-31 often used in GC) on to a silica matrix previously modified with methylvinyldiethoxysilane. The resulting phase has superior performance in reversed-phase HPLC.     

Effect of stationary phase polarity on the retention of ionic liquid cations in reversed phase liquid chromatography

Chromatographic analysis of ionic liquids on different types of packings offers interesting possibility to determine their retention mechanism. As a consequence, the major interactions between stationary phase ligands and analyzed chemical entities can be defined. The main aim of this work was to analyze cations of ionic liquids on chemically bonded stationary phases with specific structural properties. The attempt to predict the main interactions between positive ions of ionic liquids and stationary phase ligands was undertaken. For that purpose, butyl, octyl, octadecyl, phenyl, aryl, mixed, alkylamide, and cholesterolic packings were chosen and applied to the analysis of six most commonly used ionic liquids' cations. Obtained results indicate mainly dispersive and pi-pi type of interaction part in the retention mechanism of analyzed compounds.     

On the chromatography mechanism of reversed-phase liquid chromatography

Summary An equation is derived which can describe how the retention of solutes is influenced by the composition of the mobile phase in reversed-phase liquid chromatography, the retention of solutes in alkyl bonded stationary phase regarded as the complexation between solute molecule and the active sites on the surface of the stationary phase. When the stationary phase is not fully saturated by the organic modifier, the activity of the active sites, the activity coefficient of the adsorbed solute as well as the activity coefficient of the solute in the mobile phase depend on the composition of the mobile phase. However, when the stationary phase is fully saturated, the composition of the mobile phase mainly influences the activity coefficient of the solute in the mobile phase. In addition, the selectivity of retention is discussed in terms of the derived equation.     

Quantitative structure-retention relationships for ionic and non-ionic compounds in biopartitioning micellar chromatography

Quantitative structure-retention relationships, QSRRs, represent a powerful tool in chromatography. The objectives of QSRR studies are to predict the chromatographic retention behaviour of solutes based on their structural properties, to elucidate retention mechanisms, to optimize the separation of complex mixtures or to prepare experimental designs. In this paper, using the retention factors of 151 structurally unrelated solutes that cover a wide range of hydrophobicity, molecular size, hydrogen bonding properties and ionization degrees obtained in biopartitioning micellar chromatography (BMC) at different Brij35 micellar concentrations, several multivariate QSRR models are tested. It is demonstrated that the chromatographic retention of any molecule in BMC, independently of its family, can be adequately described by its hydrophobicity (expressed as log P) and its anionic and cationic total molar charge (expressed as alpha(A) and alpha(B)).     

一种新型核壳型色谱固定相在高效液相色谱中的评价及应用

采用扫描电镜、透射电镜和氮气吸附法对制备的新型核壳型色谱固定相进行了表征,结果表明该固定相单分散性好、表面放射状孔道壳层结构均一、孔径分布窄。对该核壳材料的表面进行C18键合修饰,考察其基本色谱性能,色谱柱的理论塔板数超过150000块/m,色谱峰峰形对称,甲苯与乙苯的保留因子之比为1.45,亚甲基选择性优异。将该核壳材料应用于汽车尾气中醛酮类化合物的检测,在优化的色谱条件下,2,4-二硝基苯肼（DNPH）衍生的醛酮类化合物在15 min内获得了较好的分离效果。该核壳型C18色谱固定相具有分离速度快、选择性好、柱效高等特点,适于复杂样品的高效、快速分离分析。     

反相高效液相色谱法测定糠酸、糠醇和糠醛

提出了反相高效液相色谱法（HPLC）同时测定糠酸、糠醇和糠醛的新方法,采用C18色谱柱,流动相为V（乙腈）：V（水）=50：50,流速为1.0 mL/min;检测波长为220 nm;柱温为25℃.在4 min内可以将3种组分完全分离.糠酸、糠醇、糠醛检出限（S/N=3）分别为：0.101、0.042、0.406 mg/L.平均回收率分别为101.4%、98.5%、95.3%.相对标准偏差（RSD）分别为0.87%、0.66%、0.43%.     

丁香酚键合硅胶液相色谱固定相的制备和色谱性能

采用固液相表面连续反应法,先将偶联剂γ-[(2,3)-环氧丙氧]丙基三甲氧基硅烷(KH-560)键合到球形硅胶表面,然后再将植物有效成分丁香酚与硅胶上的KH-560活性基团反应,合成了丁香酚键合硅胶液相色谱固定相(EGSP)。采用元素分析、热重分析和红外光谱对该固定相的结构进行了表征。以萘作为溶质探针,乙腈-水(35:65, v/v)为流动相,流速为0.8 mL/min,测得EGSP柱的柱效。以一系列的中性、碱性和酸性化合物为溶质探针,C₁₈柱和苯基柱作参比,对该固定相的色谱性能及保留机理进行了研究。结果表明,硅胶表面成功键合上了丁香酚配体,键合量为0.28 mmol/g, EGSP柱理论塔板数约为24707 N/m。该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含有芳环、烯基和甲氧基,还能与溶质发生π-π电荷转移、偶极-偶极和氢键作用。与传统的反相C₁₈柱和苯基柱相比,EGSP在极性芳香族化合物的快速、简便分离中占优势。     

Regioselective separation of isomeric triacylglycerols by reversed-phase high-performance liquid chromatography: stationary phase and mobile phase effects

Complete regioselective separation of five pairs of isomeric dipalmitoyl polyalkenoyl glycerols with two to six double bonds in the unsaturated acyl residues has been achieved by RP-HPLC on a single ODS column. Four ODS columns with stationary phases containing different percentages of free silanol groups have been tested. Binary mobile phases of ACN admixed with dichloromethane, tetrahydrofuran, 1-propanol, 2-propanol, ethanol, or acetone have been examined. The choice of modifier depended on the nature of the stationary phase. The more polar solvents were better suited for stationary phases with higher percentage of free silanol groups. Isomeric species were eluted according to chain length, number of double bonds, and the position of the unsaturated acyl chain in the glycerol molecule. Retention increases in the order 20:5 < 22:6 < 18:3 < 20:4 < 18:2. Within each isomeric pair, the species with unsaturated acyl chain occupying either the sn-1- or the 3-position were retained preferentially. Complete simultaneous regioselective separation of 10 isomeric triacylglycerols in a single isocratic run on a single ODS column was demonstrated.     

反相高效液相色谱法快速测定大麦籽粒中13种酚酸类化合物

建立了快速测定大麦籽粒中13种酚酸类化合物(没食子酸、原儿茶酸、绿原酸、对羟基苯甲酸、咖啡酸、香草酸、丁香酸、间羟基苯甲酸、对香豆酸、阿魏酸、藜芦酸、邻香豆酸和水杨酸)的反相高效液相色谱方法.采用SUPELCOAscentis(@) C18色谱柱(150 mm×4.6 mm,5μm)分离,流动相为甲醇-0.1％甲酸水溶...     

尿素醇解法制氨基甲酸甲酯体系的反相高效液相色谱分析

采用反相高效液相色谱法,在两根串联的C18柱上以甲醇-水为流动相,在8min内将尿素和氨基甲酸甲酯进行分离,在215nm波长下检测。在甲醇溶液中的质量浓度0~16%和0~50%范围内其峰面积和质量浓度呈良好的线性关系,线性回归方程分别为AUrea=148565x-39384,R2=0.9995;AMC=69055x-90493,R2=0.9985。     

高效液相色谱法分析硫双灭多威

研究了用高效液相色谱分析杀虫剂硫双灭多威的方法。在反相ＯＤＳ柱上,用甲醇－水作流动相,紫外检测器检测,以邻苯二甲酸二甲酯作内标定量。方法快速、准确,重现性好,线性范围宽,变异系数为０．１８％,回收率为９９．８９％,色谱分析周期仅为８ｍｉｎ。     

Retention characteristics of fluorinated bonded silica phase in reversed-phase liquid chromatography

Summary Fluorinated bonded silica has been evaluated as a packing material in reversed-phase liquid chromatography (RPLC) with polycyclic aromatic hydrocarbons, chlorinated benzenes and substituted benzenes as sample probes. The bonded material is useful as a reversed-phase stationary phase and for polar compounds it offers a specific selectivity not found with octadecylsilica (ODS) phases. The phase also retains non-planar compounds more than planar molecules. The results can be explained by conformational differences between ODS and the fluorinated bonded phase by MM2 calculation.     

Separation of racemic 2,4-dinitrophenyl amino acids on zirconia-immobilized quinine carbamate in reversed-phase liquid chromatography

Zirconia is known to be one of the best chromatographic support materials due to its excellent chemical, thermal, and mechanical stability. A quinine carbamate-coated zirconia was prepared as a chiral stationary phase for separation of enantiomers of DNP-amino acids in reversed-phase liquid chromatography. Retention and enantioselectivity of this phase were compared to those for quinine carbamate bonded onto silica. Most amino acids studied were separated on the quinine carbamate-zirconia CSP although retention was longer and chiral selectivity was somewhat lower than on the corresponding silica CSP. Increased retention and decreased selectivity are probably due to strong non-enantioselective Lewis acid-base interactions between the amino acid molecule and the residual Lewis acid sites on the zirconia surface.     

高效液相色谱手性固定相法拆分阿折地平对映体

建立了阿折地平对映体的高效液相色谱拆分方法。采用Chiralpak AD-H (250 mm×4.6 mm, 5.0 μm, Daicel公司)手性色谱柱在正相条件下直接拆分阿折地平对映体,考察了固定相种类、流动相组成及柱温等对阿折地平对映体分离的影响。确定了最佳的拆分条件: 流动相为正己烷-异丙醇(90:10, v/v),流速为0.8 mL/min,检测波长为254 nm;柱温为20 ℃;在此条件下阿折地平对映体的分离度为3.3。该法简单快速,重现性好。