Functionalized polymeric stationary phases for ion chromatography

Synthesis and properties of the multilayered stationary phases, which contain quaternary amine functional groups for the analysis of anions by ion chromatography, are described. The bonded phases were characterized by elemental analysis, solid-state (13)C NMR spectroscopy and chromatographic methods. The surface of 1,4-di(2-hydroxy-3-methacryloyloxypropoxy)phenol (solid support) was coated with polymeric layers formed by condensation polymerization of primary amine with diepoxide. Each layer of the anion exchange stationary phase consists of copolymer of methylamine (MA) and 1,4-butanedioldiglycidyl ether (BDDE). A series of stationary phases with different numbers of polymerized layers were tested. The separation of an inorganic anions sample (F(-), Cl(-), NO(2)(-), Br(-), NO(3)(-), additionally HPO(4)(2-) and SO(4)(2-)) was performed. In the measurement, a hydroxide, carbonate, bicarbonate and their mixture were used as mobile phases.     

ODS phases for ion chromatography

Several ODS phases have been dynamically modified to act as ion exchangers. Their ability to separate inorganic ions has been evaluated. The different properties of these materials are demonstrated and a method for eliminating the appearance of the system peak is described.     

Surface modification of porous graphite for ion exchange chromatography

Summary Three distinct types of weak anion exchanger have been prepared by adsorption of polyethyleneimine (PEI) on to porous graphite (PGC): PGC coated dynamically with PEI, PGC coated with. an insoluble monolayer of PEI, and PGC coated with a cross-linked polymeric PEI. Using model solutes iodate, bromide, nitrate and nitrite, dissolved in aqueous buffers, the modified PGC's show typical ion exchange behaviour, and give chromatographic performance similar to that of bonded ion-exchange silica gels. Retention is reduced by increasing the ionic strength of the buffer, and by increasing the pH. A mechanism to explain the observed trends is presented.     

亲水作用色谱及其在环境分析中的应用进展

亲水作用色谱(HILIC)是一种分离极性和亲水性化合物的液相色谱模式,其作为反相液相色谱(RPLC)的重要补充,近年来越来越受到各个领域的关注和重视。这不只是因为强极性化合物的分离问题在各个领域引起了重视,而且因为与RPLC比较,HILIC具有流动相组成黏度低、色谱柱渗透性好、与质谱联用的灵敏度高及反压较低等优势。本文简要概述了HILIC的发展历程、特点及保留机理,重点介绍了HILIC用于环境分析的最新进展,评述了HILIC及RPLC用于污染物分析的优缺点,并指出了HILIC用于环境分析的未来发展趋势。     

Preparation of polysiloxane stationary phases for capillary column chromatography: A New methoxyphenyl phase

Contemporary methods for the synthesis of alkyl- and arylsubstituted polysiloxane stationary phases are reviewed. A new, moderately polar phase containing the 3-(4-methoxyphenyl)-propyl group is reported.     

Factors affecting selectivity in ion chromatography

Methods for separation of ions by ion-exchange, ion-pair, and zwitterion ion chromatography share at least one common thread--the induced formation of a cation-anion pair in the stationary phase. Selectivity can be defined as the relative ability of sample ions to form such a pair. Examples are given in anion-exchange chromatography to show the effect of variations in the geometry, bulkiness and polarity of the resin cation on selectivity. The type of resin matrix, the hydrophobic nature of the resin surface and the degree of solvation also affect chromatographic behavior. The selectivity series observed in ion chromatography seems to be best explained by the interplay of two components: electrostatic attraction (ES) and the enforced-pairing (EP) that is brought about by hydrophobic attraction and by water-enforced ion pairing. Selectivity in ion-pair chromatography (IPC) and in zwitterion ion chromatography (ZIC) is affected by both the mobile phase cation and anion. This leads to elution orders for anions that are different from conventional ion-exchange chromatography (IC) of anions where cations are excluded from the stationary phase and have little effect on a separation. The elution order of anions in ZIC is similar to that in IC except for small anions of 2-charge, which are retained more weakly in ZIC. A unique advantage of ZIC is that sample ions can be eluted as ion pairs with pure water as the eluent and a conductivity detector. The mechanism for separation of anions on a zwitterionic stationary phase has been a subject for considerable debate. The available facts point strongly to a partitioning mechanism or a mixed mechanism in which partitioning is dominant with a weaker ion-exchange component.     

离子色谱在有机物和高分子材料分析中的应用

介绍了用氧瓶燃烧，高温炉分解有机化合物、高分子材料等样品，用去离子水或Na2CO3／NaHCO3溶液吸收分解产物，用离子色谱测定吸收液中F^-、C1^-、Br^-、SO4^2-、PO4^3-，计算出样品中氟、氯、溴、硫、磷等元素含量的方法。     

Preparation of a weak anion exchange/hydrophobic interaction dual‐function mixed‐mode chromatography stationary phase for protein separation using click chemistry

In this study, 3‐diethylamino‐1‐propyne was covalently bonded to the azide‐silica by a click reaction to obtain a novel dual‐function mixed‐mode chromatography stationary phase for protein separation with a ligand containing tertiary amine and two ethyl groups capable of electrostatic and hydrophobic interaction functionalities, which can display hydrophobic interaction chromatography character in a high‐salt‐concentration mobile phase and weak anion exchange character in a low‐salt‐concentration mobile phase employed for protein separation. As a result, it can be employed to separate proteins with weak anion exchange and hydrophobic interaction modes, respectively. The resolution and selectivity of the stationary phase were evaluated in both hydrophobic interaction and ion exchange modes with standard proteins, respectively, which can be comparable to that of conventional weak anion exchange and hydrophobic interaction chromatography columns. Therefore, the synthesized weak anion exchange/hydrophobic interaction dual‐function mixed‐mode chromatography column can be used to replace two corresponding conventional weak anion exchange and hydrophobic interaction chromatography columns to separate proteins. Based on this mixed‐mode chromatography stationary phase, a new off‐line two‐dimensional liquid chromatography technology using only a single dual‐function mixed‐mode chromatography column was developed. Nine kinds of tested proteins can be separated completely using the developed method within 2.0 h.     

Ion pair chromatography on reversed-phase layers

The results of investigations with ion pair chromatography on RP₂, RP₈ and RP₁₈ thin layers are described. Heptane sulphonic acid is used as ion pair former. The best results are achieved on RP₁₈-layers with the counter ion in the mobile phase.     

Recent advances in gas chromatography for solid and liquid stationary phases containing metal ions

This review is devoted to the application of metal complexes as column packings and liquid stationary phases in gas chromatography. Particular attention is paid to the stationary phases with nitrogen-containing functional groups (e.g., amine and ketoimine) and β-diketonates on the modified silica surface. The review also concerns the results of the research on metallomesogenes and chiral stationary phases. The factors influencing the retention mechanism in complexation gas chromatography are discussed. Practical application of the metal chelate-containing chromatographic packings for analytical separation of organic substances is considered.     

自动快速燃烧炉-离子色谱联用技术检测水泥等建材中的氯

建立了一种全新的以燃烧方法处理固体样品的装置——自动快速燃烧炉(AQF)与离子色谱联用的技术,检测建筑材料中氯的方法.该方法将AQF的快速处理样品的能力和离子色谱的准确性好、灵敏度高的特点相结合,可以连续批量处理样品,平均在18 min之内完成一个样品的检测.方法的线性、重现性、检测限均令人满意.还进行了水提法处理待测样品,将其结果与AQF处理的结果相比较,结果表明AQF处理的方法具可行性.     

Correlation ion chromatography with indirect UV detection

Summary A binary pseudo-random injection of a sample containing low concentrations of common anions into the anion exchange column was used to enhance the signal-to-noise ratio of indirect UV detection of the ions. The detection limits obtained in our experiment (14 ppb, 14 ppb, and 64 ppb for Cl^–, NO ₃ ^– and SO ₄ ^2– respectively) are in good agreement with theoretical predictions. The large amplitude system peaks inherent to single column IC do not generate remarkable ghost peaks, which is indicative of the suitability of the input devices used in our studies.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday.     

离子色谱法测定土壤中植物激素乙烯利

土壤样品中的乙烯利在IonPac AS14分离柱（4mm）,（3．5mmol Na2CO3＋1．0mmol NaHCO3）／L淋洗液的淋洗条件下得到较好的分离。在0～10μg／mL的范围内标准曲线呈线性,检出限为（0．08μg／mL）。精密度好,10．266μg／mL时,保留时间的RSD=0．86％;峰高的RSD=1．1％;峰面积的RSD=1．0％。在此条件下,其它阴离子对乙烯利的检测不干扰,样品的加标回收率为85．6％～87．9％。     

食品中亚硫酸盐的离子色谱法测定

建立了食品中亚硫酸盐的离子色谱检测方法. 样品采用40 mmol/L NaOH溶液提取, 甲醛作稳定剂, 经ENVI-Carb活性碳小柱除去提取液中的色素, 石油醚除去提取液中的油脂, 用配有电导检测器的离子色谱仪测定. 以AS9-HC为色谱柱, 流动相为8 mmol/L Na2CO3-2.5 mmol/L NaOH, 亚硫酸盐的残留量在0～6.0 mg/L的范围内线性关系良好, 相关系数为0.9989, 相对标准偏差为1.3%～9.1%, 回收率在88.4%～98.1%之间.     

Study of ion chromatography with ion-exchange fibers as the stationary phase

The application of ion-exchange fibers as the stationary phase in ion chromatography for the separation of inorganic anions has been studied. Results indicate that a separator column packed with VS-2 anion-exchange fibers and a suppressor column packed with VS-1 cation-exchange fibers have a similar separation efficiency to small-particle resin columns, but that the column pressure drop (ΔP) in fiber columns in only one-tenth of that in resin columns, at the same flow-rate. This allows the separation to be performed efficiently at a higher flow-rate and with lower presure, as shown for the separation of an anion mixture.     

Environmental applications of capillary gas chromatography coupled with atomic emission detection — a review

Environmental applications of capillary gas chromatography coupled with atomic emission derection (GC-AED) have been reviewed with emphasis on both the commercial and laboratory-built systems. Attention was focused on (1) element-selective detection of non-metallic as well as metallic pollutants, (2) identification of contaminants, and (3) sample preparation considerations.     

Effect of the chain length on the thermal and analytical properties of laterally biforked nematogens

Three laterally substituted liquid crystals were synthesized in order to investigate the effect of a lateral biforked chain on the thermal and analytical properties. The mesogenic molecules have the same core containing four aromatic rings connected by two ester and one diazo linkages, they differ by the length of one chain within the lateral biforked substituent. The phase transition temperatures were obtained by polarized light microscopy and differential scanning calorimetry (DSC). The clearing temperature and the nematic range decrease with increasing length of the lateral biforked chain. The stationary phases derived from these nematogens provide excellent resolution of various classes of compounds, including aromatic hydrocarbons (AH), substituted benzenes, polycyclic aromatic hydrocarbons (PAH), phenols and volatile organic compounds (VOC) present in the essential oils. The selectivities of the stationary phases were found to decrease according to the length of the side chain.     

Liquid-crystalline stationary phases for gas chromatography

Physico-chemical properties of new liquid-crystalline stationary phases (LCSPs) for gas chromatography are reviewed. The mechanism of chromatographic separation on liquid-crystalline stationary phases is discussed and examples of analyses of complex mixtures of organic compounds using capillary and packed columns are given.