Performance of ion chromatography in the determination of anions and cations in various natural waters with elevated mineralization

The performance of ion chromatography in the determination of anions and cations in natural mineral waters of different composition and different total mineralization was evaluated. Up to 12 ions of the 20 usually included in extended chemical analysis of natural waters were successfully determined by ion chromatography alone. At least 98.60% and up to 99.96% of total cation composition of mineral waters was determined by ion chromatography. Hydrogen carbonate predominated in anion composition of mineral waters and was determined titrimetrically. The percentage of anions determined by ion chromatography in the remaining anion composition of mineral waters was between 98.90% and 99.96%. The agreement between total concentrations of anions and cations in individual mineral waters determined predominantly by ion chromatography is very good and the performance of ion chromatography for the basic and for the extended chemical analysis of highly mineralized water samples is very high. Method development was assisted by previously developed algorithms and appropriate experimental conditions are also discussed.     

Analysis of ions in polar ice core samples by use of large injection volumes in ion chromatography

In the present study a non-suppressed ion chromatography system with conductivity detection was tested in terms of sampling effects, the effects on the ion separation efficiency and analysis detection limits to find optimum conditions for the determination of chloride, nitrate, sulfate, sodium, ammonium, potassium, calcium and magnesium ions in polar ice core samples.     

Micellar chromatography of inorganic compounds

Micellar chromatography has been used to separate various compounds and to determine the partition coefficients of the compounds between aqueous bulk solution and a micellar pseudophase. The application of this method to inorganic analyses is less common than its application to organic analyses, albeit the former application gives fundamental aspects of the micellar partition of simple ions and promises developments of novel separation. In this review, we focus our attention on the fundamental aspects of micellar chromatography mostly in inorganic analysis of simple ions.     

Preparative separation of isoflavone components in soybeans using high-speed counter-current chromatography

The analysis of ionic micro-contamination is of growing importance in the disc drive industry. Through the use of ion chromatography, cleanliness of drive components can be assessed. An objective to improve quantification of highly reactive inorganic ions that exist within the drive environment was implemented. This paper presents a new extraction technique used to determine low levels of ammonium, by microbore ion chromatography. Various chemical compounds within adhesive formulations can be a source of extractable ammonium. By combining this new extraction method with ion chromatography, the percentage of different chemical compounds within adhesive formulations was correlated to the level of extractable ammonium observed.     

Combination of suppressed and non-suppressed ion chromatography with atmospheric pressure ionization mass spectrometry for the determination of anions

Non-suppressed and suppressed ion chromatography in combination with atmospheric pressure ionization mass spectrometry are compared with special respect to sensitivity for the analysis of low-molecular-mass anions. Iodate, bromate, bromide, sulfate, thiosulfate and bromide could be separated by non-suppressed ion chromatography using a low-capacity anion-exchange column and ammonium citrate as mobile phase. Absolute detection limits between 0.4 and 0.7 ng could be achieved; employing a column requiring a flow-rate of 1 ml/min for optimum performance, splitting was necessary so that only 120 μl/min entered the interface of the mass spectrometer resulting in detection limits between 0.03 and 0.06 mg/l. The same stationary phase (packed into a narrow-bore column which allowed operation without splitting) was suitable for the separation of oxyhalides in the suppressed mode with detection limits of 0.5 μg/l (50 pg) with sodium carbonate as eluent. The method was applied to the analysis of drinking water for oxyhalides. The sample pretreatment for the removal of matrix anions (sulfate, chloride and hydrogencarbonate) is described.     

Polyelectrolyte sorbents based on aliphatic ionenes for ion chromatography

2-4, 3-4, 2-8, 3-8, 3-6, 4-6, 6-8, 6-10-ionenes (polymers with quaternary nitrogen atoms in the main chain) served as modifiers in synthesizing polyelectrolyte sorbents for ion chromatography. The approaches to the synthesis and their stability are discussed. Cluster analysis was applied to separate aliphatic ionenes to three groups as chromatographic modifiers, namely hydrophilic, hydrophobic, and intermediate. Each group is characterized by a certain selectivity to sulfate, perchlorate, iodide and thiocyanate. The sorbents show high selectivity and efficiency up to 15 000 theoretical plates per meter.     

High-capacity cation-exchange column for enhanced resolution of adjacent peaks of cations in ion chromatography

One of the advantages of ion chromatography [Anal Chem. 47 (1975) 1801] as compared to other analytical techniques is that several ions may be analyzed simultaneously. One of the most important contributions of cation-exchange chromatography is its sensitivity to ammonium ion, which is difficult to analyze by other techniques [J. Weiss, in: E.L. Johnson (Ed.), Handbook of Ion Chromatography, Dionex, Sunnyvale, CA, USA]. The determination of low concentrations of ammonium ion in the presence of high concentrations of sodium poses a challenge in cation-exchange chromatography [J. Weiss, Ion Chromatography, VCH, 2nd Edition, Weinheim, 1995], as both cations have similar selectivities for the common stationary phases containing either sulfonate or carboxylate functional groups. The task was to develop a new cation-exchange stationary phase (for diverse concentration ratios of adjacent peaks) to overcome limitations experienced in previous trails. Various cation-exchange capacities and column body formats were investigated to optimize this application and others. The advantages and disadvantages of two carboxylic acid columns of different cation-exchange capacities and different column formats will be discussed.     

Capillary zone electrophoretic determination of ionic impurities in silicone products used for electronic applications

Ionic contamination has a very negative impact on the lifetime of semiconductors and electronic devices. The ionic purity of the polymeric materials that remain in contact with active chip surfaces is regarded as a key factor to long term reliability. Currently, ion chromatography (IC) is utilised to measure and routinely control cationic and anionic contaminants (in the μg/l range) of silicone coatings and encapsulants used for electronic applications. However, this technique is expensive, time consuming and requires intensive maintenance. Capillary zone electrophoresis (CZE) has been identified as an excellent alternative to IC for the determination of extractable ionic impurities in silicone products. Main advantages of CZE for routine industrial operations are short analysis time, high sensitivity, simpler operation than IC and reduced maintenance cost.     

Lack-of-fit testing of ion chromatographic calibration curves with inexact replicates

Calibration studies involve the preparation and analysis of replicates for multiple concentrations of standards. Curves that are fitted through the data are evaluated for their adequacy of fit. A helpful test is a lack-of-fit procedure, which is performed easily by most statistical software. When coupled with R_adj², the procedure differentiates between data that are not linear and those that are simply noisy. The test requires data from replicates of the various standard levels involved. However, in ppt-level ion chromatography, the above condition may be impossible to meet. With the common anions (e.g., chloride, nitrite), the working standards must be prepared by mass and all liquids must be poured; transfer pipets contaminate at these concentrations. Since it is virtually impossible to pour out the desired mass exactly, final concentrations will vary slightly. Consequently, a different approach is needed for lack-of-fit testing. This paper discusses reasonable alternatives and applies them to actual data.     

Liquid chromatography: a tool for the analysis of metal species

An overview is presented of classic and more recent applications of liquid chromatography for the analysis of metal species. The different approaches involving ion-exchange, ion-pair, and chelation separation mechanisms are discussed as well as the new philosophy of simply removing interferents before specific detections of metal ions (alkali and alakaline earths, rare earths, heavy and transition metals). New more selective materials enabling difficult separations and studies on multimodal or hyphenated techniques for metal speciation (e.g. arsenic and chromium) are considered.     

Analysis of wastewater for anionic and cationic nutrients by ion chromatography in a single run with sequential flow injection analysis

To prevent nutrient enrichment and, hence the undesirable ecological impacts, the nutrients monitored in wastewater samples include two anionic species, i.e., nitrate and orthophosphate, and a cationic species, ammonium. Ion chromatography (IC) is one of the popularly used techniques for determinations of nitrate and phosphate in these samples, whereas determination of ammonium in wastewater samples is typically done using manual or automated wet chemistry, e.g., flow injection analysis (FIA). We have developed a sequential IC–FIA method, using Lachat’s QC8000 IC system, which allows determinations of nitrate, phosphate and ammonia in a single injection. In this system, a QuikChem Small Suppressor cartridge is regenerated in between the samples. A sample is injected while leaving the suppressor off-line. Ammonium, a cation, elutes in the void volume of an anion-exchange column. The unsuppressed column effluent, exiting the conductivity flow cell, up to this point is used for FIA determination of ammonia. When ammonia exits the conductivity flow cell, a fully regenerated suppressor is brought in-line for conductometric detection of the anions. Analog data are simultaneously acquired from colorimetric and conductometric detectors, for the cationic and anionic nutrients, respectively. The method is accurate with spike recoveries in wastewater samples ranging from 91% for nitrate to 114% for chloride. It is precise with RSD values, for replicate analyses (n=7) of a mid-range standard, ranging from 0.4% for phosphate to 1% for nitrate.     

Comparison of ion chromatography and capillary electrophoresis for the determination of inorganic ions

The techniques of ion chromatography and capillary electrophoresis are compared as analytical methods for the determination of inorganic anions and cations. Comparison is made in the areas of stage of development, separation efficiency, separation selectivity, analytical performance parameters, method development procedures, applications, strenghts and weaknesses, and future directions. It is shown that the two techniques are complementary rather than competitive, especially with regard to their separation selectivities and the type of applications to which they are most suited.     

Determination of amines used in the oil and gas industry (upstream section) by ion chromatography

During production and purification of crude oil and natural gas several different amines are used as chemicals or operating materials, e.g. film forming long chain amines as corrosion inhibitors, steam volatile amines for pH correction and corrosion protection, alkanolamines as absorbents in sour gas treatment plants, etc. For analytical checks, e.g. determination of corrosion inhibitor concentration in produced media, classical chemical methods are used predominantly, because most of them can be performed in small field laboratories. Some amines, especially the small molecular aliphatic and heterocyclic amines can also be determined by ion chromatography. In our laboratory two types of separation columns (IonPac CS10 and CS12A) were available for ion chromatographic separation. The analysis of the amines in low-salt-containing water, soft water or steam condensate can be performed without problems. The presence of alkali and/or alkaline earth ions in the sample can lead to coelution with these ions, to poor peak resolution or enhanced analysis times, depending on the chromatographic conditions. This work shows some examples of ion chromatography applications for the determination of low-mo1ecular-mass ethanolamines, morpholine and piperazine and discusses the possible interferences and troubles caused by alkali and alkaline earth ions in the matrix.     

Developments in suppressor technology for inorganic ion analysis by ion chromatography using conductivity detection

A review is presented detailing the development and use of suppression devices for the conductimetric detection of inorganic ions by ion chromatography (IC). An overview of the general response equation for conductivity detection is also given. Topics of discussion include the role and function of suppressors, the development of early suppressors including packed column and membrane devices from 1975 to 1990 and the subsequent progression towards present day commercially available suppressors and recent innovations. Post-suppression devices for signal enhancement are also discussed.     

Separation of inorganic anions by ion-pair,reverse phase liquid chromatography monitored by indirect photometry

Summary A new method for the analysis of inorganic anions is presented. It uses the most conventional liquid chromatographic system (reverse-phase chromatography) and the most common detector (ultraviolet). The nature of the ammonium ions used and their counter ions lead to different selectivities. The use of the indirect photometry allows detection of all anions.     

Evaluation on the adsorption capabilities of new chemically modified polymeric adsorbents with protoporphyrin IX

A novel stationary phase — phenylaminopropyl (PLA) bonded silica — is proposed for anion-exchange chromatography. Low basicity (pK_a about 2.5) attached to silica phenylaminopropyl groups allows a variation of surface density of protonated sites in the pH range from 2 to 5. This enables us to use the same column for the separation of anions having different affinity to anion-exchangers. The effect of mobile phase pH on conditional capacity of PhA-silica was studied. The hypothesis on dependence of ion-exchange selectivity on the column capacity is discussed. Suitability of PhA-silica for ion-chromatographic separation of organic and inorganic anions at different pH values of eluent was demonstrated.     

Electrostatic ion chromatography of polarizable anions in saline waters with N-[2-[acetyl(3-sulfopropyl)amino]ethyl]-N,N-dimethyldodecanaminium hydroxide (ammonium sulfobetaine-1) as the stationary phase and a dilute electrolytic solution as the mobile phase.

A new type of zwitterionic surfactant, N-{2-[acetyl(3-sulfopropyl)amino]ethyl}-N,N-dimethyldodecanaminium hydroxide (ammonium sulfobetaine-1), with a greater distance between the two charged groups, was used as the stationary phase for electrostatic ion chromatography (EIC) of polarizable anions (e.g., thiocyanate, iodide and nitrate) in saline water samples. The targeted species (polarizable anions) were baseline separated using this type of zwitterionic surfactant as the stationary phase, but the highly polarizable species (iodide and thiocyanate) were eluted faster (compared with the results obtained using N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate, C12N3S, with a shorter distance between the two charged groups, as the stationary phase). In other words, the extent of binding of the highly polarizable anion (iodide and thiocyanate) was found to be smaller when using ammonium sulfobetaine-1 as the stationary phase. This provides a rapid but effective method for the analysis of highly polarizable anions in saline water samples. The results for the successful detection of iodide in seawater demonstrates the usefulness of this new type of zwitterionic surfactants for EIC.     

Histidine as a dipolar eluent component in cation chromatography: II. Prediction of retention data for alkaline and alkaline-earth ions

The utility of cation chromatography has been developed by the application of -histidine as a multiprotic and dipolar (zwitterionic) eluent component. The method simplifies the cation analysis. The chromatographic characteristics of this system were studied in detail with a view to determining the selectivity and the mechanism by which the cations (Na⁺, K⁺, Mg²⁺, Ca²⁺) are retained. Complete separations were observed in the isocratic run over the eluent concentration range 3.0–6.0 mM at pH below 2.0. Sensitive detection was achieved using suppressed conductivity at the pH of isoelectric point of the histidine. Retention equations are derived for mono- and divalent cations eluted from ion-exchange separation column with multiple ionic eluents. The theory is based on the extension of ion-exchange equilibrium by protonation equilibria. The selectivity data for analyte and eluent species are determined using the model from the experimental retention data by computer-assisted iterative calculations. The model was utilized to predict retention data. The results in three-dimensional retention surfaces together with species distribution graphs are presented.     

Validation of ion chromatographic methods for the trace analysis of ions in pharmacopoeial grades of water

Ion chromatography was investigated as an alternative technique to conventional pharmacopoeial methods for the determination of inorganic anions and cations in pharmacopoeial grades of water. These methods were validated by generating data on parameters such as specificity, linearity, precision, accuracy, sensitivity, ruggedness and stability of solution. The validation data demonstrate that ion chromatography is a viable alternative technique to current pharmacopoeial methods which enables automation of pharmacopoeial water analyses.     

Simultaneous determination of anions and cations by ion-exclusion chromatography–cation-exchange chromatography with tartaric acid/18-crown-6 as eluent

Ion-exclusion chromatography–cation-exchange chromatography was developed for the simultaneous separation of common inorganic anions and cations (Cl⁻, NO₃⁻ and SO₄²⁻; Na⁺, NH₄⁺, K⁺, Mg²⁺ and Ca²⁺) on a weakly acidic cation-exchange column by elution with weak acid. Generally, the resolution among these monovalent cations was only moderate, thereby hindering the determination of these analytes in natural-water samples. Therefore, 18-crown-6 was added to the eluent to improve the resolution. A good separation of these anions and cations on a weakly acidic cation-exchange column was achieved in 30 min by elution with 5 mM tartaric acid/6 mM 18-crown-6/methanol–water (7.5:92.5). The ion-exclusion chromatography–cation-exchange chromatography method developed here was successfully applied to the separation of major anions and cations in an environmental water sample.