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1.
This paper describes an electrostatic ion chromatographic system in which the separation selectivity for inorganic anions, especially for sulfate and phosphate, could be manipulated by altering the molar ratio of the zwitterionic and cationic surfactants in the column coating solution used to prepare the stationary phase. The zwitterionic surfactant used for this study was 3-(N,N-dimethyltetradecylammonio)propanesulfonate (Zwittergent-3-14) and the cationic surfactant was tetradecyltrimethylammonium (TTA). Using a reversed-phase C18 column (250×4.6 mm I.D.) coated with 10/10 (mM/mM) of TTA/Zwittergent-3-14 mixed micelles as the stationary phase and either NaHCO3 or Na2CO3 aqueous solution as the eluent, together with suppressed conductivity detection, baseline separation of seven model inorganic anions was obtained. The elution order for those anions was found to be F42−42−23. Under the same conditions but using 1/10 (mM/mM) of TTA/Zwittergent-3-14 mixed micelles as the column coating solution, the elution order for these model ions was F42−42−23. The early elution of phosphate and sulfate is a unique attribute of this system. Detection limits for F, HPO42−, Cl, SO42−, NO2, Br and NO3 (S/N=3, sample injection volume 100 μl) were 0.11, 0.12, 0.12, 0.18, 0.49, 0.49, 0.52 μM, respectively.  相似文献   

2.
A new method has been developed for ion-interaction chromatography with suppressed conductivity detection and a new graphitized carbon packing, which is sintered from carbonic material at a high temperature. Combinations of various eluting agents, tetrabutylammonium hydroxide (TBA) and acetonitrile have been investigated to optimize the separation of eight common anions (F, Cl, NO2, Br, NO3, SO42−, HPO42− and I). Calibration curves were linear from 0.5 to 10 μg/ml for F, from 1.0 to 20 μg/ml for Cl, NO2 and NO3, from 2.5 to 50 μg/ml for Br and SO42− and from 5.0 to 100 μg/ml for HPO42− and I with a correlation coefficient (r) of 0.999 or better. The relative standard deviations (R.S.D.s) of peak areas were between 0.2 and 0.9% for 10 repeated measurements. The application of this newly developed method was demonstrated by the determination of chloride, bromide and sulfate in pharmaceutical compounds using the direct injection method. The analytical results were within ±2% (relative) of the theoretical value, and thus in good agreement with the theoretical value for each sample.  相似文献   

3.
As a part of the European EUROCORE and GRIP (Greenland Ice Core Project) operations aimed at recovering deep ice cores at Summit (Central Greenland), we have for the first time successfully performed ion chromatography measurements in the field and investigated in detail the soluble impurities, including Na+, NH+4, K+, Mg2+, Ca2+, F, CH3COO, CH2 OHCOO, HCOO, CH3SO3, Cl, NO2, SO42− and C2O42−, trapped in ice deposited over some 200 000 years in Greenland.  相似文献   

4.
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.  相似文献   

5.
Organic-rich natural waters from peat bogs in continental (Switzerland) and maritime (Shetland Islands, Scotland) areas were analysed for Cl, NO2, Br, NO3, HPO42−, SO42− and oxalate using ion chromatography. These anions can be determined simultaneously in the surface and pore water samples from the continental bogs using a 250-μl injection loop. Using this loop, the detection limits were ca. 5 ng/g for the monovalent anions and SO42− and 10 ng/g for HPO42− and oxalate. An organics-removal cartridge (Dionex OnGuard P) was used to remove humic materials. These cartridges did not significantly affect the measured concentrations of anions in blind standards. Analyses of deionized water treated with these cartridges are not significantly different from those for untreated deionized water. For the maritime bogs, the relatively high concentrations of Cl (more than 100μ/g in many samples) and SO42− (up to 50 μg/g) require two separate determinations for complete analyses. A 10-μl injection loop was used to determine Cl, Br and SO42−. A 250-μl injection loop was used to measure NO2, NO3, HPO 42− and oxalate. In each instance a Dionex OnGuard P cartridge was used to remove humic materials. In addition, a chloride-removal cartridge (Dionex OnGuard AG) was used to remove Cl when the larger injection loop was used. This cartridge has no significant effect on the measurement of HPO4-2− at concentrations of 20 ng/g. In each of the bog water chromatograms there were usually a number of unknown peaks. These are probably due mainly to organic anions.  相似文献   

6.
The performance of medium-quality ion chromatographic equipment was improved by using pseudo-random sample intoduction correlation chromatography (CC). The importance of the digital preprocessing of the detector signal prior to decorrelation was demonstrated for realization of the multiplex advantage of the CC method. The detection limits obtained for single-column ion chromatography using conductivity were 0.1, 0.12, and 0.17 ppm for Cl, NO3 and SO42− ions, respectively. Using the same apparatus without CC the detection limits are in the range 1–3 ppm.  相似文献   

7.
8.
Amberlite XAD-2 has been functionalized by coupling it, through the ---N=N--- group, with Pyrocatechol Violet (PV), and the resulting resin has been characterized by elemental analysis, thermogravimetric analysis (TGA) and IR spectra. The resin has been used for preconcentrating Zn(II), Cd(II), Pb(II) and Ni(II) ions prior to their determination by flame atomic absorption spectrometry. The optimum pH values for quantitative sorption are 5, 5–7, 4, and 3 for Zn, Cd, Pb and Ni, respectively. The four metals can be desorbed (recovery ˜98%) with 4 M HNO3; also, 4 M HCl is equally suitable except for Zn. The sorption capacity of the resin is 1410, 1270, 620 and 1360 μg g−1 resin for Zn, Cd, Ni and Pb, respectively. The effect of F, Cl, NO3, SO42− and PO43− on the sorption of these four metal ions has been investigated. They are tolerable in the range 0.01–0.20 M, for Pb. In the sorption of Zn(II) and Ni(II), the tolerance limits of all these ions are upto 0.01 M, whereas for Cd(II), F, NO3, and PO43− have been found to be tolerable upto 0.50, 0.10 and 0.10 M, respectively. The preconcentration factors are 60, 50, 23 and 18 for Zn, Cd, Pb and Ni, respectively. Simultaneous collection and determination of the four metals are possible. Cations commonly present in drinking water do not affect the sorption of either metal ion if present at a concentration level similar to that of water. The method has been applied to determine Zn, Ni and Pb content of well-water samples (RSD ≤9%).  相似文献   

9.
A new application of capillary electrophoresis for measuring major and trace anions in thermal water and condensed-steam samples is presented. Ten fluid samples were collected from hydrothermal springs and fumaroles located in a volcanic zone of Deception Island, Antarctica. Anion separation was achieved in less than 6 min using indirect UV detection at 254 nm with a negative power supply (−15 kV). The electrolyte consisted of 4.7 mM sodium chromate, 4.0 mM electroosmotic flow modifier (OFM) hydroxide, 10 mM 2-(N-cyclohexylamino)ethanesulfonic acid and 0.1 mM calcium gluconate (pH 9.1). Major anions (Cl, SO42, PO4H2−, and CO3H) were measured using hydrostatic injection (10 cm for 30 s) at 25°C. Trace amounts of anions (F, Br, and NO3) were better determined by electromigration injection (4 kV, 10 s) at 15°C. Good reproducibility of the migration times (<0.72% RSD), a satisfactory linear response and accuracy as well as acceptable detection limits were successfully obtained.  相似文献   

10.
A monitoring system consisting of a portable-type conductimetric ion-exclusion–cation-exchange chromatographic (CEC) analyzer and a meteorological satellite data analyzer has been investigated for the evaluation of the effects of acid precipitation on natural and urban environments in East Asia. The portable ion-exclusion–CEC analyzer uses a polymethacrylate-based weakly acidic cation-exchange resin column in the H+-form and a weak-acid eluent (tartaric acid–methanol–water) and is applied for the simultaneous determination of anions (SO42−, NO3, and Cl) and cations (Na+, NH4+, K+, Mg2+, and Ca2+) in precipitation transported from mainland China to central Japan, as mapped by the meteorological satellite data analyzer. Linear calibration graphs of peak area versus concentration for anions and cations were observed in the concentration range 0–1.0 mM for the anions and 0–0.5 mM for the cations. Detection limits at a signal-to-noise ratio of 3 were in the range 5.18–12.1 ppb for the anions and 6.58–16.5 ppb for the cations. The practical utility of this monitoring system is presented.  相似文献   

11.
Corrosion of aluminum alloy structures costs the US Air Force in the order of US$1×109 annually. Corrosion develops in areas of overlap such as aircraft lap-splice joints and under protective organic coatings. Capillary electrophoresis (CE) has been used to determine the local chemistries at these corrosion sites of solutions that were extracted using a microsampling system. Analysis of the local solution within lap-splice joints from aircraft has been performed in two ways: rehydration of corrosion products and direct microsampling. The solutions collected were analyzed with CE to quantitatively determine the species present during corrosion. The most common ions detected were Cl, NO2, NO3, HCO3, K+, Al3+, Ca2+, Na+ and Mg2+. Studies of the solution chemistry under local coating defects are required to understand coating failure and develop more durable coatings. A microsampling system and micro pH sensor were developed to extract solution from and measure pH in defects with diameters as small as 170 μm. Actively corroding defects contained high concentrations of Cl, Al3+, Mg2+, Mn2+ and Cu2+ whereas only trace levels of Mg2+ were found in repassivated defects. The effects of these species on initiation and propagation of corrosion are discussed.  相似文献   

12.
Nanophotocatalysis using nanostructured semiconductors constitute one of the emerging technologies for destructive oxidation of organics such as dyes. This paper deals with the decolorization and mineralization of reactive dyes by heterogeneous nanophotocatalysis using an immobilized TiO2 nanoparticle photocatalytic reactor. A simple and effective method was used to immobilization of titanium dioxide nanoparticles. Reactive Orange 107 (RO 107, sulphatoethylsulphonyl reactive dye) and Reactive Red 152 (RR 152, monochlorotriazine reactive dye) were used as model compounds. UV–vis and ion chromatography (IC) analyses were employed to obtain the details of the photocatalytic degradation of the selected dyes. The effects of operational parameters such as H2O2, dye concentration, anions (NO3, Cl, SO42−, HCO3 and CO32−) and pH were investigated. Formate, acetate and oxalate anions were detected as dominant aliphatic intermediates where, they were further oxidized slowly to CO2. Nitrate, sulfate and chloride anions were detected as the photocatalytic mineralization of RO 107 and RR 152. Kinetics analysis indicates that the photocatalytic decolorization rates can usually be approximated zero-order model for RO 107 and first-order model for RR 152 dyes. Results show that the photocatalytic process occurred at solution bulk and the employment of optimal operational parameters may lead to complete decolorization and mineralization of dye solutions.  相似文献   

13.
The paper reports results of a study on the specific adsorption of F, Cl, Br, I, ClO3, BrO3, IO3 and IO4 on hydrous γ-Al2O3. The isotherms of the anion adsorption and the adsorption dependencies on pH and the ionic strength of the solution have been determined under the equilibrium conditions. According to the degree of affinity to γ-Al2O3, the anions can be ordered as: I3334−. It has been established that the sorption of IO4 and F involves the formation of surface complexes in the inner co-ordination sphere, whereas that of Cl, Br, I, ClO3, BrO3 and IO3 takes place through formation of ion pair complexes in the outer co-ordination sphere. In the dynamic system, the exchange isoplanes and elution curves have been determined for selected anions on columns filled with Al2O3. It has been shown that γ-Al2O3 can be used for isolation and concentration of IO3 from natural waters in order to decrease the limit of the ions determination to 2 μg l−1. Using differential pulse voltammetry (DPV), after isolation and concentration on γ-Al2O3, the content of iodates has been determined in mineral, marine and tap water doped with these ions.  相似文献   

14.
Putative free-radical intermediates in drug action can be studied by radiolysis of model systems containing low concentrations of drug and much higher concentrations of other solutes to scavenge the primary water radicals and convert them into appropriate oxidants or reductants. The need to employ high ionic solute concentrations (typically >10 mmol dm−3) represents a challenge for the high-performance ion chromatographic detection of drug-derived ions (typically, <50 μmol dm−3). Constraints on the chromatographic method chosen are illustrated with examples of the application of high-performance ion chromatography (HPIC) to radiation chemistry studies in the oxidative decar☐ylation of the anti-tumour drugs flavone-8- and xanthenone-4-acetic acids and structurally related aromatic car☐ylic acids (CO2 in the form of CO32−), the oxidative denitrification of nitric oxide precursor molecules (NO in the form NO2/NO3) and the generation of SO42− from novel thiol-based (perthiol) drugs.  相似文献   

15.
De Marco R  Phan C 《Talanta》2003,60(6):1215-1221
The direct flow injection potentiometric (FIP) analysis of phosphate in hydroponic nutrient solution has been carried out using a cobalt-wire ion-selective electrode (ISE). Synthetic hydroponic nutrient solution, commercial hydroponic nutrient solution and working hydroponic farm nutrient solution were analysed for phosphate using the FIP technique. It is shown that FIP results compare favourably to standard methods of analysis such as spectrophotometry and indirect photometric ion-pair chromatography. Reproducible FIP response curves with a slope of −(47.57±0.03) mV per decade and intercept of −(169.7±0.1) mV were obtained for four separate calibrations in the concentration range 5.0×10−4–1.0×10−2 M H2PO4. Anion corrections for interferences by Cl, NO3 and SO42− were applied to all samples using the selectivity coefficients determined independently using a fixed interference method. Nevertheless, it was found that anion corrections were not necessary, as the deviations fell within the bounds of experimental error for the cobalt-wire ISE technique (i.e.±2–5% R.S.D.). The proposed FIP method enables the direct determination of phosphate in hydroponic nutrient solutions.  相似文献   

16.
复杂水盐体系存在稳态和介稳固液相平衡以及复杂的成盐规律。为了解固液平衡状态下液相的结构特征,本文采用拉曼光谱技术并结合高斯-洛伦兹去卷积分峰拟合程序对Na+, Mg2+//SO42-, Cl-, H2O四元体系及其二元和三元子体系中ν1-SO42-的离子缔合结构特征进行了分析。研究结果表明:SO42-在Na2SO4-H2O体系存在自由态SO42-和SO42-离子簇两种结构,在MgSO4-H2O, MgSO4-MgCl2-H2O及Na+, Mg2+//SO42-, Cl-, H2O等含镁体系中,还有Mg2+-H2O-SO42-和Mg2+-OSO32-两种缔合结构。在二元和三元体系中ν1-SO42-的离子缔合结构以自由态SO42-为主,随着SO42-离子总浓度的变化,上述四种结构所占比例会发生规律性变化。Na+, Mg2+//SO42-, Cl-, H2O四元体系在NaCl减少及等温蒸发过程中,自由态SO42-结构比例逐步降低, Mg2+和SO42-相结合形成Mg2+-H2O-SO42-或Mg2+-OSO32-结构的机会增多,在复盐区还会形成SO42-离子簇结构。由此判断溶液结构的适应性变化是导致介稳现象的重要原因。进一步的相关分析表明:SO42-的浓度和耶涅克指数Jν1-SO42-峰的峰强度和峰面积存在正相关关系, Mg2+浓度是影响ν1-SO42-峰中四种缔合结构的比例发生变化的主要因素。  相似文献   

17.
The rate constant for the reaction between the sulphate radical (SO4√−) and the ruthenium (II) tris-bipyridyl dication (Ru(bipy)32+) is (3.3±0.2)×109 mol−1 dm3 s−1 in 1 mol dm−3 H2SO4 and (4.9±0.5)×109 mol−1 dm3 s−1 in 0.1 mol dm−3, pH 4.7 acetate buffer. The SO4√−radical produced by the electron transfer quenching of Ru(bipy)32+* by S2O82− reacts rapidly with both acetate buffer and chloride ions. These side reactions result in a reduction in the overall quantum yield of Ru(bipy)33+ production and reduced reaction selectivity when Ru(bipy)32+* is quenched by persulphate.  相似文献   

18.
Leachates from different areas of a modern hazardous-waste landfill were investigated. In addition, samples of the waste to be buried were taken, and leachability tests in accordance with German standards were performed. The composition of the leachates from the landfill and the leachates produced by the leachability tests varied over a wide range, depending on the kind and volume of hazardous waste buried and the weather conditions. High concentrations of some anions were often found in combination with low concentrations of other anions. In the leachates the following concentration ranges were found: Cl, 30–6000 mg/l; NO2, 0–150 mg/l; NO2, 0–150 mg/l; SO2 2−, 100–6000 mg/l. Therefore, several dilutions of one sample often had to be measured. The complex matrix often also requires several sample preparation steps for the elimination of interfering effects. Experience to date has shown that ion chromatography in this application field is efficient.  相似文献   

19.
Ki Soo Kim  Hong-Seok Kim   《Tetrahedron》2005,61(52):765-12370
A new molecular tweezer receptor Hc1 based on hyodeoxycholic acid has been synthesized and its binding properties were accessed by 1H NMR and isothermal titration calorimetry experiments. Molecular tweezer Hc1 shows a high selectivity toward F over Cl, Br, I, and H2PO4.  相似文献   

20.
Matos RC  Coelho EO  Souza CF  Guedes FA  Matos MA 《Talanta》2006,69(5):1208-1214
The importance of atmospheric hydrogen peroxide (H2O2) in the oxidation of SO2 and other compounds has been well established. A spectrophotometric method for the determination of hydrogen peroxide in rainwater is proposed. This method is based on selective oxidation of hydrogen peroxide using an on-line tubular reactor containing peroxidase immobilized on Amberlite IRA-743 resin. The hydrogen peroxide in the presence of phenol, 4-aminoantipyrine and peroxidase, produces a red compound (λ = 505 nm). Beer's law is obeyed in a concentration range of 1–100 μmol l−1 hydrogen peroxide with an excellent correlation coefficient (r = 0.9991), at pH 7.0, with a relative standard deviation (R.S.D.) <2%. The detection limit of the method is 0.7 μmol l−1 (4.8 ng of H2O2 in a 200 μl sample). Measurements of hydrogen peroxide in rain samples were carried out over the period from November 2003 to January 2005, in the central area of the Juiz de Fora city, Brazil. The concentration of H2O2 varied from values lower than the detection limit to 92.5 μmol l−1. The effects of the presence of nonseasalt (NSS) SO42−, NO3 and H+ in the concentration of hydrogen peroxide in the rainwater had been evaluated. The average concentrations of H2O2, NO3, NSS SO42− and SO42− are 23.4, 18.9, 7.9 and 10.3 μmol l−1, respectively. The pH values for 82% of the collected samples are greater than 5.0. The spectrophotometeric method developed in this work that uses enzyme immobilized on the resin ion-exchange compared with the amperometric method did not present any significant difference in the results.  相似文献   

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