Separation of inorganic anions by liquid chromatography with crown ether as eluent additive

Inorganic anions were separated on a reversed-phase stationary phase dynamically modified with crown ether as a selector in capillary ion chromatography. The eluent contained crown ether, acetonitrile and a salt. Free and cation-trapped crown ether molecules in the eluent were adsorbed on a hydrophobic stationary phase such as triacontyl-functionalized silica (C30). The eluent cations trapped on crown ether worked as the ion-exchange sites, where the eluent anions and the analyte anions were competing for electrostatic interaction. The sizes of crown ether and the salt cation affected the retention of analyte anions. The concentrations of acetonitrile and crown ether as well as the eluent anion also affected the retention of analyte anions. An aqueous solution containing 18-crown-6-ether, potassium salt and acetonitrile achieved larger retention for analyte anions. Effects of the eluent conditions on the retention of analyte anions were examined in detail.     

Organic solvent and temperature-enhanced ion chromatography-high resolution mass spectrometry for the determination of low molecular weight organic and inorganic anions

There has recently been increased interest in coupling ion chromatography (IC) to high resolution mass spectrometry (HRMS) to enable highly sensitive and selective analysis. Herein, the first comprehensive study focusing on the direct coupling of suppressed IC to HRMS without the need for post-suppressor organic solvent modification is presented. Chromatographic selectivity and added HRMS sensitivity offered by organic solvent-modified IC eluents on a modern hyper-crosslinked polymeric anion-exchange resin (IonPac AS18) are shown using isocratic eluents containing 5–50 mM hydroxide with 0–80% methanol or acetonitrile for a range of low molecular weight anions (<165 Da). Comprehensive experiments on IC thermodynamics over a temperature range between 20–45 °C with the eluent containing up to 60% of acetonitrile or methanol revealed markedly different retention behaviour and selectivity for the selected analytes on the same polymer based ion-exchange resin. Optimised sensitivity with HRMS was achieved with as low as 30–40% organic eluent content. Analytical performance characteristics are presented and compared with other IC-MS based works. This study also presents the first application of IC-HRMS to forensic detection of trace low-order anionic explosive residues in latent human fingermarks.     

Novel imidazolium stationary phase for high-performance liquid chromatography

A new imidazolium anion-exchange phase immobilized on silica is synthesized. HPLC separations of common inorganic anions (IO3-, Cl-, NO2-, Br-, NO3-, I-, SCN-) have been performed using a HPLC column (200 mm x 4.6 mm I.D.) packed with this stationary phase, with a phosphate buffer solution as the mobile phase and UV detection at 200 nm. The effects of pH and concentration of eluent on the separation of anions have been studied. Chromatographic parameters are calculated and the results show that the new stationary phase is of significant potential for the analysis of these anions. Successful separations of some ordinary organic anions have also been achieved with the said stationary phase. Meaningfully, organic and inorganic anions can be determined simultaneously and satisfactorily with several neutral compounds using the column. The separation of some organic compounds including hydroxybenzenes, bases and amines by this stationary phase with only water as the eluent has been investigated.     

整体柱离子相互作用色谱快速分析无机阴离子

研究了用硅胶整体柱和直接电导检测的离子相互作用色谱快速分析常见无机阴离子的方法。实验采用氢氧化四丁铵和邻苯二甲酸为淋洗液,讨论了包括淋洗液浓度、流速和pH对分离的影响。当以1.5 mmol/L氢氧化四丁铵和1.1 mmol/L邻苯二甲酸为淋洗液(pH 5.5),流速6 mL/min时,可以在1 min内分离Cl-、NO2-、Br-、NO3-、ClO3-、SO42-和I-7种阴离子。方法的检出限为0.3~1.9 mg/L,峰面积、峰高的相对标准偏差(RSD,n=5)分别为0.4%~2.2%和0.1%~1.5%。将该法用于测定矿泉水和地下水中的阴离子,加标回收率在97.9%~100.3%之间。     

Analysis of low-molecular-mass inorganic and organic anions by ion chromatography-atmospheric pressure ionization mass spectrometry.

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.     

Influence of acidic eluent for retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography on a weakly acidic cation-exchange resin in the H+ -form

Influence of acidic eluent on retention behaviors of common anions and cations by ion-exclusion/cation-exchange chromatography (ion-exclusion/CEC) were investigated on a weakly acidic cation-exchange resin in the H(+)-form with conductivity. Sensitivities of analyte ions, especially weak acid anions (F(-) and HCOO(-)), were affected with degree of background conductivity level with pK(a1) (first dissociation constant) of acid in eluent. The retention behaviors of anions and cations were related to that of elution dip induced after eluting acid to separation column and injecting analyte sample. These results were largely dependent on the natures of acid as eluent. Through this study, succinic acid as the eluent was suitable for simultaneous separation of strong acid anions (SO(4)(2-), Cl(-), NO(3)(-) and I(-)), weak acid anions (F(-), HCOO(-) and CH(3)COO(-)), and cations (Na(+), K(+), NH(4)(+), Mg(2+) and Ca(2+)). The separation was achieved in 20 min under the optimum eluent condition, 20 mM succinic acid/2 mM 18-crown-6. Detection limits at S/N=3 ranged from 0.10 to 0.51 microM for strong acid anions, 0.20 to 5.04 microM for weak acid anions and 0.75 to 1.72 microM for cations. The relative standard deviations of peak areas in the repeated chromatographic runs (n=10) were in the range of 1.1-2.9% for anions and 1.8-4.5% for cations. This method was successfully applied to hot spring water containing strong acid anions, weak acid anions and cations, with satisfactory results.     

Influence of organic solvents in the mobile phase on the determination of carboxylic acids and inorganic anions in grape juice by ion chromatography

Investigations have been initiated to develop a sufficiently good separation of both major and minor organic acids and inorganic anions present in grape musts using a Dionex As11 column, a sodium hydroxide gradient elution and a suppressed conductivity detection. Separation was complicated in aqueous mobile phase by co-elutions and selectivity was optimized using organic modifiers that alter ion-exchange selectivity for hydrophobic ions. In this study, the influence of three different solvents (methanol, ethanol and acetonitrile) on the efficiency of column was compared. The best separation of all ions in a synthetic solution was achieved with an eluent containing 13% (v/v) methanol and 13% (v/v) ethanol in water, the run during only 20 min. This method was next applied to grape juices with success and has shown sensitivity and reproducibility. Moreover, sample preparation was a simple 20-fold dilution with 0.45 microm filtration and direct injection without prior sample clean-up.     

Determination of monovalent inorganic anions in high-ionic-strength samples by electrostatic ion chromatography with suppressed conductometric detection

A new ion chromatographic (IC) system has been established by using micelles of 3-(N,N-dimethylmyristylammonio)propanesulfonate (Zwittergent 3-14) loaded onto a reversed-phase packed column as the separation column with an electronic rotary switching valve packed-bed suppressor for conductometric detection of inorganic anions. An aqueous H3BO3-Na2B4O7 solution has been demonstrated to be the most desirable eluent for this IC system. The relationship between retention time and the concentration of the borate eluent was determined for a series of model anionic analytes and this relationship was found to be opposite to that exhibited in a conventional anion-exchange IC system. The rapid elution and complete separation of monovalent inorganic anions were obtained by initially using a high-concentration borate solution as the eluent for a short-period, and then switching to a lower-concentration borate eluent to complete the separation. Detection limits for nitrite, bromide, nitrate, and chlorate were 0.85, 0.88, 0.95 and 4.8 microM, respectively, when a 7.0 mM Na2B4O7 eluent was used. Moreover, the ability to directly detect these monovalent anions in samples containing high concentrations of sulfate and/or chloride ions provided a major advantage of this approach.     

离子色谱法同时分析董酒中的有机酸与无机阴离子

研究了用离子色谱法同时分析董酒中可离解性有机酸和无机阴离子。首次采用邻苯二甲酸氢钾和邻苯二甲酸的混合水溶液作淋洗剂,改善了分离效果,提高了检测灵敏度。所建立的方法无需进行样品前处理,无干扰,有一定的实用价值。     

Determination of trace concentrations of bromate in municipal and bottled drinking waters using a hydroxide-selective column with ion chromatography

The International Agency for Research on Cancer determined that bromate is a potential human carcinogen, even at low micro/l levels in drinking water. Bromate is commonly produced from the ozonation of source water containing naturally occurring bromide. Traditionally, trace concentrations of bromate and other oxyhalides in environmental waters have been determined by anion exchange chromatography with an IonPac AS9-HC column using a carbonate eluent and suppressed conductivity detection, as described in EPA Method 300.1 B. However, a hydroxide eluent has lower suppressed background conductivity and lower noise compared to a carbonate eluent and this can reduce the detection limit and practical quantitation limit for bromate. In this paper, we examine the effect of using an electrolytically generated hydroxide eluent combined with a novel hydroxide-selective anion exchange column for the determination of disinfection byproduct anions and bromide in municipal and bottled drinking water samples. EPA Methods 300.1 B and 317.0 were used as test criteria to evaluate the new anion exchange column. The combination of a hydroxide eluent with a high capacity hydroxide-selective column allowed sub-microg/l detection limits for chlorite, bromate, chlorate, and bromide with a practical quantitation limit of 1 microg/l bromate using suppressed conductivity detection and 0.5 microg/l using postcolumn addition of o-dianisidine followed by visible detection. The linearity, method detection limits, robustness, and accuracy of the methods for spiked municipal and bottled water samples will be discussed.     

Analysis of oligosaccharides using aminobonded silica gel and a ternary eluent with evaporative light scattering detection

Using two commercial, amino bonded, silica gel columns, binary eluents (methanol/water, acetonitrile/methanol) and ternary eluents (acetonitrile/methanol/water) are evaluated for their ability to separate oligosaccharides in comparison with classical acetonitrile/water eluents. Chromatographic data on glucose, maltose, raffinose, stachyose and maltodextrin are reported. Mobile phases consisting of acetonitrile/water or acetonitrile/methanol/water produce the best separations. Phase hydrolysis is evaluated using an evaporative light scattering detector. The reduction of the water content in the eluent stabilizes the aminocolumns and the life time of the amino columns should be improved with the ternary eluent. Moreover, a better detection limit can be obtained. Capabilties to run gradient elution without baseline drift are clearly demonstrated.     

离子色谱法测定饮用和地下水中氟化物、溴酸盐、氯化物、亚硝酸盐、硝酸盐、硫酸盐

建立离子色谱法测定饮用和地下水中F-、BrO3-、Cl-、NO2、NO3和SO42- 6种阴离子.选用IonPac(R)AS19色谱柱(4 mm×250 mm),NaOH梯度淋洗,抑制电导检测,方法检出限为0.01～0.02 mg/L.对水样进行6次平行测定,测定结果的相对标准偏差为1.1％～2.1％,加标回收率为71...     

The determination of lactate,acetate, chloride and phosphate in an intravenous solution by non-suppressed ion chromatography

Summary The determination of acetate, lactate, chloride and phosphate in an intravenous solution is investigated using non-suppressed ion chromatography with indirect UV absorption detection. When phthalate eluents are used with low capacity anion-exchange columns, the above solute species cannot be resolved unless acetonitrile is added to the eluent. Optimum results are obtained with 0.3 mM phthalate (pH 6.0) containing 30% acetonitrile as eluent. The improved resolution with this eluent is attributed to the existence of a partial reversed-phase retention mechanism operating on the unfunctionalised portions of the styrene-divinylbenzene polymeric ion-exchange material.     

反相离子对色谱中有机溶剂浓度和离子对试剂浓度对保留值的影响

我们测定了氨基苯磺酸和氨基萘磺酸在反相离子对色谱中不同乙腈/水, 甲醇/水配比和离子对试剂浓度下的保留值,并把两种冲洗剂下的保留值和关系式lnk'=a+C~c~b中的参数a,C作线性关联,得到很好的相关性,这表明有机溶剂乙腈和甲醇对选择性并无显著的影响,但乙腈有更大的冲洗强度.证明关系式lnk'=A+Blnc~p+C~c~ b能较好地描述有机溶剂和离子对试剂浓度对保留值的影响, 但当离子对试剂浓度较高时该关系式不成立.同时提出了有机溶剂浓度和离子对试剂浓度"等同效应" 的概念     

HPLC Determination of Amino And Carbonyl Compounds with Dabsyl Chloride and Dabsyl Hydrazine

The new chromophoric reagent, 4-dimethylaminoazobenzene-4′-sulfonyl chloride (dabsyl chloride) was synthesized by reaction of sodium 4-dimethylaminoazobenzene 4′-sulfonate with phosphorus pentachloride. Dabsyl chloride reacted rapidly with all amino acids, aliphatic amines, and polyamines to form the corresponding dabsyl derivatives. The dabsyl amino acids (10^?11 mol) were visualized on thin layer plates and found to be photo-stable. During the last 12 years, in combination with HPLC, this newly developed labeling reagent has been shown to be very promising for microdetermination of amino acids, aliphatic amines and polyamines. Recently, another new chromophoric reagent, dabsylhydrazine, was synthesized from the reaction of dabsyl chloride with hydrazine. This reagent reacted readily with monosaccharides and carbonyl compounds to form the corresponding chromophoric dabsylhydrazones with strong absorbance at 425 nm. The application of this new reagent in HPLC analysis of monosaccharides was discribed. By use of Nova-PAK C₁₈ reverse-phase column and a concave gradient system of water and acetonitrile as eluent, the detection limits of monosaccharides in the range of 10 pmol have been reached.     

2-羟基萘甲醛苯腙衍生物对氟阴离子的高选择性裸眼识别

合成了3种2-羟基萘甲醛苯腙衍生物[1～3;取代基R:H(1),p-NO2(2),2,4-d-NO2(3)],应用紫外-可见吸收光谱研究了其与阴离子的相互作用,通过改变N1-苯环取代基考察了受体分子对阴离子亲合力和选择性的影响.结果表明,乙腈中F-及CH3COO-等阴离子使受体分子吸收光谱发生显著变化,溶液的颜色由黄色...     

Influence of Physicochemical Parameters of Some Ring-Substituted Phenol Derivatives on Their Retention on a Porous Graphitized Carbon Column

Abstract

The retention characteristics of 29 phenol derivatives were determined on a porous graphitized carbon column in unbuffered acetonitrile—water and methanol—water eluent mixtures at various organic phase concentrations. Each phenol derivative showed symmetric peaks in each eluent without buffers. Good linear correlations were found between the log k' value and the organic mobile phase concentration in the eluent. Principal component analysis indicated that methanol and acetonitrile expose different selectivities. Stepwise regression analysis proved that the retention of ring—substituted phenol derivatives is mainly governed by the sterical parameters, electron-withdrawing power and hydrogen donor capacity of substituents. According to the results of Free-Wilson analysis, the substituents with large steric parameters, strong electron-withdrawing power and hydrogen donor capacity have the highest impact on the retention. The lipophilicity of phenol derivatives did not affect significantly the retention, although the eluents were typical reversed-phase eluents.     

Use of zwitterionic micelles in the eluent: a new approach for ion chromatographic (IC) analysis of ions in biological fluids with direct sample injection

The problem of column performance degradation due to irreversible binding of proteins encountered in ion chromatographic (IC) analysis of ions in protein-containing samples was overcome by using zwitterionic micelles (e.g., Zwittergent-3-14) as a portion of the eluent. A zwitterionic micellar eluent showed high ability for solubilization of proteins, and, hence, the protein-containing samples could be analyzed without need for deproteinization. On the other hand, the zwitterionic micelle was insensitive to conductivity but interacted with the analyte ions, due mainly to its unique configuration of charges (namely, the zwitterionic micelle containing both positively and negatively charged groups but carrying no net charge). Using a zwitterionic micellar eluent, the analyte ions could be detected selectively and sensitively, and moreover, the selectivity for the analyte ions was unique. A conventional anion-exchange column conditioned with a Zwittergent-3-14 micellar eluent was applied for the analysis of real biological samples (serum and urine) with direct sample injection. The results of the successful detection of inorganic anions (Cl-, SO4(2-), NO2-, Br-, and NO3-) have demonstrated the usefulness of this new IC approach for the analysis of biological samples.     

离子色谱法测定净水产品中F-、Cl-、NO-2、No-3、HPO2-4和SO2-4

建立了离子色谱法测定净水产品中的F<'->、Cl<'->、NO<'-><,2>、No<'-><,3>、HPO<'2-><,4>和SO<'2-><,4>6种阴离子.根据净水产品的类型分别选择配制水浸提和直接净化配制水两种方法处理样品,选用IonPac As9-HC色谱柱(250 mm×4 mm),8.0 mm0L/L N...