Ion exchange chromatography of aluminum using 3-carboxy-2-naphthylamine-N,N-diacetic acid as a fluorescent post-column chelating reagent

Ion exchange chromatography of aluminum ion using 3-carboxy-2-naphthylamine-N,N-diacetic acid (CNDA) as a fluorescent post-column chelating reagent was studied. The solution containing ammonium chloride and hydrochloric acid was used for the eluent, and acetate buffer solution containing CNDA was used for the post column chelating reagent. The peak of aluminum was separated from that of calcium, magnesium and zinc, and the chromatogram was not affected by copper(II) and iron(III). The calibration curve gave linear plots with a range of 0.0027-0.54 ppm aluminum, the regression coefficient of correlation (r2) was 1.000, and the detection limit (S/N = 3) was 0.3 ppb, indicating that the method could determine aluminum with high sensitivity. It was demonstrated that CNDA is a useful metallofluorescent reagent for aluminum. This method has been successfully applied to the determination of aluminum in some tea drinks.     

Determination of copper(II) based on its catalytic effect on thiosemicarbazide-H(2)O(2)-CTMAB chemiluminescence reaction

A novel chemiluminescence (CL) reaction, thiosemicarbazide (TSC)–H₂O₂, for the determination of copper at nanogram per milliliter level in batch type is described. The method is based on the catalytic effect of copper(II) on the oxidation of TSC with hydrogen peroxide to produce light emission. The emitted light was observed by using a conventional fluorescence detector. In the optimum conditions, calibration graph was linear in the range of 0.1–1.3 ppm. The limit of detection was 10 ppb. The relative standard deviation for five determinations of 0.5 ppm copper(II) was 1.93%. The proposed method permitted the selective and sensitive determination of Cu(II) in human hair and wheat flour with sufficient precision. The possible mechanism for the new chemiluminescence reaction was also discussed.     

Uniformly sized molecularly imprinted polymer for d-chlorpheniramine. Evaluation of retention and molecular recognition properties in an aqueous mobile phase

Rapid separation and determination of mixtures of L-ascorbic acid, nitrite, sulfite, oxalate, iodide and thiosulfate by conventional ion chromatography is often difficult due to incomplete separation of L-ascorbic acid and nitrite from the water peak when using eluents giving short elution times for iodide and thiosulfate. Separation of the six species within about 15 min has been achieved by isocratic elution using a resin-based ion-exchange column with a carbonate eluent containing a trace amount of 1,3,5-benzenetricarboxylic acid (BTA) and fluorescence measurement of cerium(III) formed via postcolumn reactions of the separated sample species with cerium(IV). Calibration plots of peak height versus concentration were linear up to 10.0 microM (1.76 ppm) for L-ascorbic acid, 8.0 microM (0.37 ppm) for nitrite, 8.0 microM (0.70 ppm) for oxalate, 80.0 microM (10.2 ppm) for iodide and 25.0 microM (2.80 ppm) for thiosulfate, whilst the sulfite calibration was linear up to 25.0 microM (2.00 ppm) when peak area was plotted against concentration. Detection limits (defined as S/N = 3) were 18 ppb for L-ascorbic acid, 4 ppb for nitrite, 16 ppb for sulfite, 7 ppb for oxalate, 72 ppb for iodide and 37 ppb for thiosulfate. The proposed method was applied successfully to the determination of L-ascorbic acid, nitrite, sulfite, oxalate, iodide or thiosulfate in water samples.     

Preconcentration of trace chalcophile elements by a zincon--loaded resin and its application to neutron activation analysis (author's transl)]

A chelating agent-loaded resin consisting of an anion exchange resin and zincon which has widely been employed as a specific reagent for zinc(II) and copper(II) in spectrophotometry was prepared. The adsorption behavior of some chalcophile elements was studied in detail, with respect to pH, flow rate and exchange capacity. From the results, it was confirmed that the zincon-loaded resin reacts selectively with copper(II), zinc(II), mercury(II) and lead(II) at lower pH region, and the above reaction is stoichiometric as in the case of the reaction of zincon with metal ions in aqueous solution. Furthermore, the zincon-loaded resin was applied to the selective concentration of trace amounts of chalcophile elements in natural water samples prior to neutron activation analysis. Water samples taken from the Watarase River were filtered and the pH of each filtrate was adjusted to ca. 5.5. After preconcentration was made by the column method (zincon-loaded resin: 2 x 10-4 mol/g resin, 1.0 g, 7 mm phi x 35 mm), the resin in the column was washed and dried in a desiccator. The standard material was also prepared according to the above mentioned scheme. The sample and the standard materials packed in polyethylene vials were irradiated for 40 min by a neutron flux of 5 x 10(13 n.cm-2.sec-1 in the JRR-4 of the Japan Atomic Energy Research Institute. After cooling the materials, activity measurements were made. The results were 53 ppb for copper, 0.25 ppb for mercury.     

Histidine as the functional group for a chelating ion exchanger

In the chelating ion exchanger synthesized, the amino group of histidine is attached chemically via the azide method to the carboxyl group of Amberlite IRC-50. A flow system based on a spectrophotometric detector, with 4-(2-pyridylazo) resorcinol as reagent, is described for fast assays of eluted cations. The pH dependence of the metal extraction is reported for Ag(I), Au(III), Cu(II), Fe(III), Hg(II), Ni(II) and Zn(II) ions. The resin exhibits no affinity for the alkali or alkaline earth metals. The uptake of traces of the specified elements from synthetic samples by a short (90 mm) column of the histidine-containing resin was in the range 94–100% and the retained metals were readily eluted by means of 2 M hydrochloric or hydrobromic acid. In column operation, mercury was quantitatively recovered even in the presence of large excesses of various ligands. The recoveries of the trace metals were good at the usual pH of natural waters.     

8-Quinolinol-5-sulfonic acid-loaded resin as a preconcentrating agent in the neutron activation analysis of the chalcophile elements (author's transl)]

A chelating agent-loaded resin consisting of 8-quinolinol-5-sulfonic acid and an anion-exchange resin (HOx-resin) was prepared in order to concentrate trace chalcophile elements in natural water samples selectively before neutron activation analysis. The exchange capacity of the Diaion SA No. 100 for the reagent (1.8 meq . g-1 resin) corresponds approximately to that for chloride ion (1.83 meq . g-1 resin), indicating that 8-quinolinol-5-sulfonic acid is adsorbed quantitatively on the exchange site of the resin through the sulfonate anion in the reagent. The basic conditions for the adsorption of the metal ions on the resin were investigated by employing the column method. The nitrate concentration and the pH of the sample solution affect the adsorption behavior of metal ions. Several solutions containing metal ions with varying pH or varying nitrate concentration were applied to the resin column (35 mm x 7 mm phi) with a flow rate of 2.0 cm3 . min-1. As a result, the optimum conditions for the quantitative adsorption of copper(II), zinc(II), cadmium(II), cobalt(II), nickel(II) and manganese(II) were as follows: NO3- less than 0.01 mol . dm-3 pH greater than 4.6. Furthermore, the feasibility of the above conditions as well as quantitative adsorption of the chalcophile elements was confirmed through the neutron activation analysis of the synthesized metal solutions.     

Azocalix[4]pyrrole Amberlite XAD-2: New polymeric chelating resins for the extraction, preconcentration and sequential separation of Cu(II), Zn(II) and Cd(II) in natural water samples

Two novel azocalix[4]pyrrole Amberlite XAD-2 polymeric chelating resins were synthesized by covalently linking diazotized Amberlite XAD-2 with calix[4]pyrrole macrocycles. The chelating resins were used for extraction, preconcentration and sequential separation of metal ions such as Cu(II), Zn(II) and Cd(II) by column chromatography prior to their determination by UV/vis spectrophotometry or flame atomic absorption spectrophotometry (FAAS) or inductively coupled plasma atomic emission spectroscopy (ICP-AES). Various parameters such as effect of pH on absorption, concentration of eluting agents, flow rate, total sorption capacity, exchange kinetics, preconcentration factor, distribution coefficient, breakthrough capacity and resin stability, were optimized for effective separation and preconcentration. The resin showed good ability for the separation of metal ions from binary and ternary mixture on the basis of pH of absorption and concentration of eluting agents. The newly synthesized resins showed good potential for trace enrichment of Cu(II), Zn(II) and Cd(II) metal ions, especially for Cu(II), as compared to the earlier reported resins. The synthesized resins were recycled at least 8-10 times without much affecting column sorption capacity. The presented method was successfully applied for determination of Cu(II), Zn(II) and Cd(II) in natural and ground water samples.     

Determination of copper at ng levels by in-line preconcentration and flow-injection analysis coupled with flame atomic-absorption spectrometry

Oxine/formaldehyde/resorcinol and oxine/formaldehyde/hydroquinone resins have been synthesized and their physicochemical properties studied. Conditions were optimized for the preconcentration of copper by batch extraction and column chromatography with the resins. A flow-injection analysis (FIA) manifold was constructed for the determination of copper at ng levels by preconcentration on microcolumns containing the resins, stripping, and atomic-absorption spectrometry. For batch preconcentration a pH of about 2.5-3 was optimal whereas in the FIA system a broader pH range (approximately 2-3.5) could be used. Separations of binary mixtures of Cu(II) with Ni(II) or PB(II) at microg/ml level did not show any cross-contamination. In the FIA, a 2 cm long column and 2 ml/min flow-rate were adequate for quantitative uptake of copper; 50 micro1 of 0.1M hydrochloric acid quantitatively eluted the copper.     

Automated separation and preconcentration of copper(II) from natural waters using a column treatment

Summary A comparison is made between two automated column procedures for the separation and preconcentration of Cu(II) from natural waters. The column materials were: an anion-exchange resin and 8-hydroxyquinoline immobilized on a glass support. 8-Hydroxyquinoline showed about the same performance as the ion exchange resin, but was less time and labour consuming. Cu(II) determinations at the ppb level were checked with standard additions and the results were moreover compared with those obtained by another method.On leave from Lisbon University, Portugal     

Bulk acoustic wave sensor for the ion chromatographic determination of copper in human plasma

By using ion chromatography with series bulk acoustic wave detection, a method for the determination of copper in human blood plasma has been developed. The advantages of the good selectivity of ion chromatography and the highly sensitive response of SBAW have been combined to improve detection limit, accuracy and reproducibility. The detection limit (3) of the method to copper is 0.3 g/ml. The relative standard deviation for the determination of 1.0 g/ml of copper is 2.1% (n=7). For the IC analysis, the analytical column is a Shim-pack IC C1 column, and the mobile phase is 4.0 mM tartaric acid/2.0 mM ethylenediamine solution with pH 4.2. This system has been applied to the determination of Cu in blood plasma from healthy people or patients with renal failure.     

Pt‐Nanoparticle Incorporated Carbon Paste Electrode for the Determination of Cu(II) Ion by Anodic Stripping Voltammetry

Pt‐nanoparticles were synthesized and introduced into a carbon paste electrode (CPE), and the resulting modified electrode was applied to the anodic stripping voltammetry of copper(II) ions. The synthesized Pt‐nanoparticles were characterized by cyclic voltammetry, scanning electron microscopy and X‐ray photoelectron spectroscopy techniques to confirm the purity and the size of the prepared Pt‐nanoparticles (ca. 20 nm). This incorporated material seems to act as catalysts with preconcentration sites for copper(II) species that enhances the sensitivity of Cu(II) ions to Cu(I) species at a deposition potential of ?0.6 V in an aqueous solution. The experimental conditions, such as, the electrode composition, pH of the solution, pre‐concentration time, were optimized for the determination of Cu(II) ion using as‐prepared electrode. The sensitivity changes on the different binder materials and the presence of surfactants in the test solution. The interference effect of the coexisted metals were also investigated. In the presence of surfactants, especially TritonX‐100, the Cu(II) detection limit was lowered to 3.9×10^?9 M. However, the Pt‐nanoparticle modified CPE begins to degrade when the period of deposition exceeds to 10 min. Linear response for copper(II) was found in the concentration range between 3.9×10^?8 M and 1.6×10^?6 M, with an estimated detection limit of 1.6×10^?8 M (1.0 ppb) and relative standard deviation was 4.2% (n=5).     

Copper(II) determination by means of a thermometric method based on its catalytic effect on the hydrazine-hydrogen peroxide reaction

A new catalytic-thermometric method for Cu(II) determination at ppb levels has been established based on the hydrazine-hydrogen peroxide redox reaction. The reaction rate is obtained from the temperature-time curve and shows two linear response zones, between 15–200 ppb and 0.1–0.9 ppm, with a relative standard deviation of 2.0% and 2.2%, respectively. Only 20 ppm of Pb(II) and Fe(III), 1 ppm of Mn(II) and 5 ppb of Co(II) interfere. Interferences of Pb(II) and Fe(III) can be eliminated by the use of maskings. The proposed method can be applied to determine Cu(II) in several samples. In the present paper, this method has been applied to determine Cu(II) in wine.     

Chiral speciation and determination of DL-selenomethionine enantiomers on a novel chiral ligand-exchange stationary phase.

A new type of chiral ligand-exchange stationary phase (CLES) was successfully synthesized by treating silica gel with beta-(3,4-epoxycyclohexyl)ethyltrimethoxy silane and opening the epoxy ring by L-isoleucine. The chiral speciation of DL-selenomethionine (DL-SeMet) by high-performance liquid chromatography (HPLC) with UV absorbance on the CLES column was studied. The influences of the contents of copper ion and methanol as well as the pH value in the mobile phase and temperature of the column on the efficiency of resolution of DL-SeMet were investigated in detail. DL-SeMet could be completely resolved within 40 min under the optimal operating conditions of 0.1 mmol/L Cu2+ at 0.05 mol/L KH2PO4 buffer (pH = 5.5) and 35 degrees C temperature of the column. The limits of detection of D- and L-SeMet were 255 ppb and 286 ppb, respectively. This method was applied to determine the D- and L-enantiomers of DL-SeMet in real samples, such as selenized yeast powder and garlic.     

Two-column ion-exchange method for the determination of copper-complexing capacity and conditional stability constants of copper complexes for ligands in natural waters

Sample solutions titrated with Cu(2+) ions are passed sequentially through two ion-exchange columns in an automated flow system. The first column is packed with Chelex-100 resin and retains Cu(2+) ions that are free or derived from copper complexes that dissociate in the column. The second column is packed with AG MP-1 anion-exchange resin and retains negatively charged Cu(II) complexes. The retained copper species are then eluted from the columns and determined on-line with a flame atomic-absorption spectrophotometer. It is necessary to correct for a small fraction of free Cu(2+) ions that pass through the first column and are retained by the second column. The Cu(II)-complexing capacity of sample solutions is determined from plots of the concentration ratio of free Cu(2+) ions to Cu(II) complexes vs. the concentration of free Cu(2+) ions. Conditional stability constants of the copper complexes are also estimated from these plots. The complexing capacity of sample solutions is also determined rapidly by measuring the concentration of complexed Cu(II) after spiking the sample with an excess of Cu(2+) ions. The sample solutions tested were 4.0muM NTA, 4.0-mg/l. humic acid, and a river water.     

Determination of heavy metals by isotachophoresis

The suitability of isotachophoresis for the analysis of metals in, e.g., environmental samples was studied. In a cationic operational system the heavy metals Fe, Cu, Ni, Cd, Co, Zn, Pb and Mn were simultaneously determined. The separation was achieved through complex formation with one of the counter ions, hydroxyisobutyric acid. The other counter ion was acetic acid, the leading ion was 0.02 M potassium or sodium (pH 4.1) and the terminator was H+. The analysis time was 15 min at 60 microA in a 0.2 mm I.D. capillary. Aqueous samples containing ppm and ppb amounts were enriched on a cation exchanger with an extremely low affinity for sodium (Chelex 100). Good recovery, linearity, precision and accuracy were obtained even down to the ppb range. Although the sensitivity of the method is not greater than that of some of the more established methods for the individual metals, a great advantage of isotachophoresis is the simultaneous determination of the metals, with equal response factors. An example is given of the determination of metals, including aluminium, in serum.     

Application of dithiocarbamate resin-metal complexes as stationary phases in gas chromatography

A chelating resin with dithiocarbamate functional groups to which silica gel was used as a matrix and silanes were used with diamino functional groups as a spacer was synthesized. The structure and the conversion of functional groups of the resin were confirmed by IR spectra and elemental analysis. The influence of pH on the adsorption of the resin for metal ions was also examined. The resin under optimum pH conditions formed a 1:1 metal complex with copper ion. The affinity of metal ions toward the synthesized resin decreased in the order Hg(II) >; Cu(ll) >; Cd(II) >; Zn(II). The resin exhibited efficient complexation of transition metal cations. The cadmium, copper and zinc complexes were investigated for application as stationary phase for the gas chromatographic analysis of dialkyl sulphides. The material was packed in a 2.1 m × 3.2 mm I.D. spiral glass column. Factors affecting the retention and sample selectivity were also studied. A shorter retention time and sharp peaks were obtained when ammonia was introduced into the mobile phase. At an oven temperature of 100°C, a flow-rate of 60 ml min⁻¹ and use of a flame ionization detector, the analysis of dialkyl sulphides showed that the copper resin complex as the stationary phase gave the best results. The stationary phase was also used for the separation of dialkyl sulphide from a hydrocarbon mixture.     

Chemiluminescence investigation of NH(2)OH-fluorescein-Cu(2+) system and its application to copper analysis in serum

A novel chemiluminescent system, fluorescein-NH(2)OHOH(-), was developed for the determination of copper(II) in serum. A weak light emission arises from hydroxylamine in the presence of the organic reagent fluorescein in basic aqueous solution. Under the conditions of 1.2 x 10(-3) mol l(-1) NH(2)OH and 5 x 10(-3) mol l(-3) fluorescein, the light intensity is linearly dependent upon the concentration of copper(II) within the range 1-20 ppb. The relative standard deviation of the determination of copper(II) is 4.2% (n = 13) and the detection limit is 0.5 ppb. The system is highly selective for copper except in the presence of iron(II,III) and cobalt(II). In conjunction with potassium fluoride as masking agent, the method was successfully applied to the determination of microamounts of copper(II) in serum. A mechanistic study of the chemiluminescence reaction is also discussed.     

Catalytic flow-injection determination of sub-ppb copper(II) using the redox reaction of cysteine with iron(III) in the presence of 2,4,6-tris(2-pyridyl)-1,3,5-triazine.

A kinetic-catalytic spectrophotometric flow-injection method was developed for the rapid and sensitive determination of trace amounts of copper(II). The method is based on the catalytic effect of copper(II) on the redox reaction of cysteine with iron(III). Iron(II) produced by the catalytic reaction reacts with 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) to form the iron(II)-TPTZ complex (lambda(max) = 593 nm). By measuring an absorbance of the complex, one could determine 0.05-8 ppb copper(II) with the relative standard deviations (n = 10) of 1.6%, 1.3%, and 0.8% for 0.5 ppb, 1 ppb, and 2 ppb copper(II), respectively. The limit of detection (S/N = 3) was 0.005 ppb. The sample throughput was 30 h(-1). The proposed method was successfully applied to the determination of copper in natural water and serum samples.     

Preparation and Analytical Application of a New Chelating Ion Exchange Resin Containing Thioglycolic Acid

Starting from copolymerization of acrylonitrile and divinylbenzene by emulsion polymerization technique, a macroporous, crosslinked polyacrylonitrile copolymer was synthesized. The nitrile groups on the copolymer resin were converted into carboxylic acid groups by hydrolysis with strong alkaline solution of sodium hydroxide to obtain the resin matrix with carboxylic acid groups. A new chelating ion exchange resin containing alkylthioglycolate was prepared by esterification of carboxylic acid groups on the resin matrix and thioglycolic acid with 1,6-hexanediol as binding part. After studies of the basic characters, ion exchange ability, exchange rate and acidity of the medium, it was found that the new resin obtaind was highly selective for silver(I), mercury(II), gold(III) and bismuth(III) in acidic-aqueous solution. Separation of these metal ions from each other and concentration of these metal ions from very dilute solution were studied by liquid chromatography using a short column of this new resin. The analytical applications of this new resin are reported.     

Preparation and properties of a chelating resin containing the nitrosoresorcinol group

A macroreticular polystyrene-based chelating resin with the nitrosoresorcinol group as the functional group has been synthesized. The resin shows selectivity for copper(II), iron(III), and cobalt(II). The sorption behaviour of cobalt(II) is examined in detail, with the intention of using the resin analytically. Iron(III) and cobalt(II) are separated in a column operation by stepwise elution with oxalic acid solution and hydrochloric acid respectively.