Low-capacity Anion-exchange Column Research Articles

Simultaneous determination of iodide and iodate in povidone iodine solution by ion chromatography with homemade and exchange capacity controllable columns and column-switching technique

A simple ion chromatographic method for simultaneous detection of iodide and iodate in a single running was proposed, with columns packed with homemade functionalized polystyrene-divinylbenzene (PS-DVB) resins and column-switching technique. Homemade resins were functionalized with controllable amounts of quaternary ammonium groups. The low-capacity anion-exchange column and high-capacity anion-exchange column were prepared, due to the resins having different exchange capacities. With this method, iodide and iodate in povidone iodine solution were detected simultaneously in a short time with iodide being eluted off first. A series of standard solutions consisting of target anions of various concentrations from 0.01mg/L to 100mg/L were analyzed. Each anion exhibited satisfactory linearity, with correlation coefficient r≥0.9990. The detection limits (LODs) for iodide and iodate obtained by injecting 100μL of sample were 5.66 and 14.83μg/L (S/N=3), respectively. A spiking study was performed with satisfactory recoveries between 101.2% and 100.6% for iodide and iodate.

Simultaneous determination of bromide and nitrate in contaminated waters by ion chromatography using amperometry and absorbance detectors

This study describes a new ion chromatography method using a low-capacity anion exchange column with amperometric and absorbance detection for rapid and simultaneous determination of Br − and NO 3 − in contaminated waters where one of these ions is present in excess compared to other. The use of two detectors overcomes the problem of baseline separation for Br − and NO 3 − for accurate quantification, which was commonly encountered when using a low-capacity anion exchange column and suppressed conductivity detection mode. The method achieved accurate quantification of these two ions without requirement of baseline separation. The accuracy of 2.8% for NO 3 − was determined using a quality control sample obtained from UN GEMS/Water PE Study No. 6. The detection limits for Br − and NO 3 − were 20 and 6 μg l −1 (25 μl sample), respectively. Linearity of these two ions was over three orders of magnitude with a correlation coefficient >0.998. The influence of potential interfering ions was also studied followed by the determination of Br − and NO 3 − in seawater, unsaturated zone water, soil extract and groundwater.

DETERMINATION OF FLUORIDE IONS BY SINGLE COLUMN HIGH PRESSURE ANION CHROMATOGRAPHY IN DENTIFRICE PREPARATIONS AND BODY FLUIDS: SALIVA AND BLOOD SERUM

Fluoride ions are commonly used as anticaries agents in dentifrice preparations. However, when the fluoride level exceeds the recommended limits some fluorosis may be noticed. This paper focuses on the single column ion chromatographic determination of fluoride using conductometric detection. Chromatography was achieved on a low capacity anion exchange column, Hamilton PRP-X100 150 × 4.1 mm, 10 μm, with a low conductivity mobile phase consisting of 4 mM p-hydroxybenzoic acid and 0.5 mM sodium benzoate (pH 9.0 adjusted with 1 N NaOH) at a flow rate 1.8 mL/min. For the quantitative determination, peak height was used, while in some cases bromide can be used as internal standard (suggested concentration 15 mg/L). A rectilinear relationship was observed up to 30 mg/L. The limit of detection (S/N = 3) was 1 ng, while the limit of quantitation (LOQ) was 5 ng at 0.1 μS, when 50 μL of the samples were injected onto the analytical column. The time of analysis is less than 3.5 min. The statistical eval-uation of the method was examined performing within-day (n = 8) and inter-day calibration (n = 8) with RSD values rang-ing from 2.6 to 5.2 and from 7.1 to 11.7 respectively. The applicability of the method was demonstrated in the analysis of sodium fluoride dentifrices: lozenges, toothpastes, mouth wash solutions, as well as in body fluids: saliva and blood serum. Recovery of fluoride ions in spiked body fluid samples ranged from 91.7 to 110.1%.

Simultaneous determination of six inorganic anions in drinking water by non-suppressed ion chromatography

A non-suppressed ion chromatographic method with conductometric detection is described for the simultaneous determination of six inorganic anions: fluoride, chloride, nitrite, bromide, nitrate and sulphate. The separation was achieved on a low-capacity anion-exchange column Metrohm IC Anion Column Super Sep, with a mobile phase consisting of phtalic acid dissolved in high-purity water, 2-amino-2-hydroxymethyl-1,3-propendiol and acetonitrile. In this work computer optimization procedures, using computer programs to select chromatographic conditions have been used, leading to the achievement of a desired separation. By using the different optimization methods in an integrated manner it is, however, possible to both speed method development, by reducing unnecessary experimentation, and to overcome the many shortcomings of each method, because of the different approaches. The purpose of this work is to improve and characterise the method for simultaneous determination of six inorganic anions in drinking water by non-suppressed ion chromatography, using optimization procedures, in order to be applied to the routine analysis. The proposed method has numerous advantages over the other widely used non-suppressed ion chromatography methods: higher selectivity, shorter analysis time, lower quantitation and detection limits. The performance characteristics of the method were established by determining the following validation parameters: precision and accuracy, linearity, detection limits and quantitation limits.

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.

Photometric Ion Chromatographic Determination of Anionic Species with Novel Eluents

Retention and nonsupressed ion chromatographic separations of inorganic and organic anions on a low-capacity anion exchange column using indirect UV detection has been examined. Several novel eluents drawn from hydroxy- and amino-substituted benzoic acids have been evaluated and found effective in trace analysis and speciation of simple and complex anionic analytes. A novel eluent, 4-hydroxy-3-aminobenzoic acid, is proposed for quantification of halides, oxyhalides, and pseudohalides in aqueous environmental and commercial samples.

Highly Selective Simultaneous Determination of Eight Inorganic Anions in Drinking Water by Single Column High Pressure Anion Chromatography

Abstract Ion Chromatography is a well-established analytical technique for the simultaneous determination of ions. This paper focuses on the analytical determination of eight inorganic anions: fluoride, hydrogen carbonate, chloride, nitrite, bromide, nitrate, hydrogen phosphate and sulphate, using conductometric detection. The separation of the cited anions was achieved on a low capacity anion exchange column Hamilton PRP-X100 100 × 4.1 mm, 10 μm, with a mobile phase consisted of 2.5 mM p-hydroxybezoic acid and 2.0 mM sodium benzoate at a pH 9.0 adjusted with 1N NaOH and 8% Ch3OH as organic modifier, at a flow rate 0.7 ml/min. For the quantitative determination bromide was used as internal standard at a concentration of 7.8 mg/l. A rectilinear relationship was observed up to 40 mg/l for all ions except for carbonate that was up to 30 mg/l. The detection limits (S/N = 3) were 100 μg/l for carbonate and 50 μg/l for the rest of the cited anions, when 50 μ/l of the samples were injected onto the analytical co...

The Isocratic Separation and Indirect Uv Detection of Inorganic Anions and Mono- and Di-Carboxylic Acids On A Low-Capacity Anion Exchange Column

Abstract The isocratic separation of inorganic anions, and mono-and di-carboxylic acids on a low-capacity anion exchange column using indirect UV detection was studied. Retention of organic analyte anions on low-capacity anion exchange columns has been attributed to anion exchange, adsorption, or a combination of the two. Previous studies (1) were used to provide the mobile phase conditions for this study. It was found that the mobile phase pH. under the conditions used, had a major affect on the separation and resolution of the different analyte anions studied. Isocratic separations for a complex mixture of inorganic anions, and mono- and di-carboxylic acids at different mobile phase pH's are shown.

Indirect UV Detection of Organic Analyte Anions Using a Low-Capacity Anion Exchange Column

Abstract Organic analyte anion retention on a low-capacity anion exchange column using indirect UV detection was studied. A combination of anion exchange/reversed-phase interactions were found to influence the retention of organic analyte anions provided the analytes have both an anionic charge site and a hydrophobic center. Organic analyte anion retention was found to be influenced by the following: concentration of organic modifier, concentration of UV absorbing analyte, pH, and mobile phase ionic strength. Correlation coefficients of better than 0.999 were found for several of the organic and inorganic analytes studied. Detection limits of 0.5 to 1.0 ppm were observed.

Determination of selenate by single-column ion chromatography

Chromatographic parameters were optimized to determine selenate (SeO 2− 2) by single-column ion chromatography with the simultaneous detection of Cl −, NO − 2, NO − 3 and SO 2− 4. Separation was conducted on a low-capacity anion-exchange column, and anions were quantified by conductimetric detection. The eluent stream consisted of 4 m M phthalic acid adjusted to pH 4.6 with sodium borate. Accurate measurement of trace amounts of SeO 2− 4 was evident in the presence of high background levels of other ions including Cl −, NO − 3 and up to 40 mg l −1 SO 2− 4. Resolution of SeO 2− 4 and SO 2− 4 was demonstrated up to 80 mg l −1 SO 2− 4. The detection limit of SeO 2− 4 was 18 μg l −1 with a relative standard deviation of 1.46%.

Determination of nitrate and nitrite in cured meats using high-performance liquid chromatography

Several existing chromatographic techniques for the determination of nitrate and nitrite were evaluated and found to be unsuitable for the analysis of cured meats because of interferences present in these samples. An alternative procedure was developed, based on the use of a low capacity anion-exchange column with chloromethanesulphonate as eluent, and using ultraviolet absorbance at 210–214 nm as the detection method. This analytical method was shown to be rapid, sensitive and precise, and satisfactory recovery was observed when nitrate and nitrite were added to several food samples. A comparison of this method with a conventional spectrophotometric method showed poor agreement between the two techniques and is attributed to deficiencies in the spectrophotometric method. The proposed chromatographic procedure is shown to be applicable to the analysis of vegetables and cheese as well as cured meats.

Ion chromatography of nucleobases, nucleosides and nucleotides using a dual-detection system

The retention behaviour of nucleobases, nucleosides, and nucleotides has been systematically investigated using ion chromatography with a hollow fibre ion-exchange membrane suppressor. A low-capacity anion-exchange resin column and sodium carbonate buffer or sodium phosphate buffer eluents were employed for the separation of these compounds. The effects of concentration and pH of the mobile phase on the retention behaviour of twelve nucleotides was studied in detail. A conductivity detector was used for the detection of inorganic anions as well as organic compounds along with a UV detector. Optimum conditions for the rapid separation of nucleobases, nucleosides, nucleotides and their mixtures using carbonate and phosphate buffers are reported.

Separation and Detection of Arsenical Pesticide Residues and Some of Their Metabolites by High Pressure Liquid Chromatography-Graphite Furnace Atomic Absorption Spectrometry

Abstract A method was developed for the separation and quantitative determination of arsenite, methanearsonic acid (MAA), dimethylarsinic acid (cacodylic acid or CA), and arsenate by high pressure liquid chromatography (HPLC) coupled to a graphite furnace atomic absorption (GFAA) detector. The compounds are separated on a low capacity anion exchange column with gradient elution from 100+ water-methanol (80 + 20, v/v) to 100% 0.02M (NH4)2CO3-methanol (85 + IS, v/v) at 1.2 mL/min and a pressure of about 300 psi. The HPLC was coupled by an automatic sampling unit to the GFAA through an interface consisting of a Teflon flow-through sampling cup. Limit of detection for the arsenic compounds was about 5 ng As injected in aliquots of 20 μL (0.25 ppm As in solution). All 4 arsenical compounds gave similar calibration curves, which were linear from 0.1 to 2.0 ng for single atomizations in the GFAA and from 5 to 200 ng when multiple, sequential atomizations of HPLC eluant were used to quantitate HPLC peaks. Quenching by soil extracts as well as aqueous HPLC solvents was minimal.