Separation of metal ions by capillary electrophoresis

A number of experimental parameters have been optimized for the separation of 26 metal ions, including alkali, alkaline earth, transition and lanthanide metal ions. Experimental parameters that were evaluated included nature of indirect-detection reagent, pH of electrolyte, concentration of complexing agent and nature of the surface of the capillary; unbonded and C₁ and C₁₈ bonded phases were studied. In addition the effect of internal diameter on linearity and signal-to-noise ratio was examined, and separation efficiency was determined for a variety of experimental conditions. Detection limits (signal-to-noise RATIO = 3) were ca. 1 μg/ml for the lanthanides, ca. 0.6 μg/ml for transition and alkaline earth ions and ca. 0.1–0.8 μg/ml for alkali metal ions. The average relative standard deviations of were 3.7, 5.1 and 2.5% on unbonded, C₁ and C₁₈ capillaries, respectively. Whereas conventional regression analysis suggested that the calibration curves were linear over the range of 1·10⁻⁵ to 4·10⁻⁴ mol/l, sensitivity plots showed that the results were actually linear to within 6% only over the range of 2.5·10⁻⁵ to 4·10⁻⁴ mol/l.     

Separation of noble metal ions on silica with chemically bonded ligands

The separation of noble metal ions was investigated by chemically bonded ligands based on the concept of hard and soft acids and bases according to Pearson; influences of ion pairing and chelating effects are discussed. Complexing groups containing oxygen, nitrogen and sulphur were immobilized on silica gel. Ag, Au, Ir, Os, Pd, Pt and Rh were adsorbed in the acidic range (pH 0 to pH 5) and eluted from the gel in the range from pH 0 to pH 7.5 avoiding formation of hydroxides and coprecipitation of the noble metals. The separation is dependent on the immobilized ligand, the pH-value of sorption and desorption and the eluent.     

Separation of metal ions by capillary electrophoresis with a complexing electrolyte

Excellent separations of metal ions can be obtained very quickly by capillary electrophoresis provided a weak completing reagent is incorporated into the electrolyte to alter the effective mobilities of the sample ions. Indirect photometric detection is possible by also adding a UV-sensitive ion to the electrolyte. Separations are described using phthalate, tartrate, lactate or hydroxyisobutyrate as the complexing reagent. A separation of twenty-seven metal ions was achieved in only 6 min using a lactate system. A mechanism for the separation of lanthanides is proposed for the hydroxyisobutyrate system.     

Separation of metal ions in nitrate solution by ultrasonic atomization

In the ultrasonic atomization of metal nitrate solutions, the molar ratio of metal ions is changed between solution and mist. Small molar metal ions tend to be transferred to mist by ultrasonic wave acceleration, while large molar ions tend to remain in solution. As a result, metal ions can be separated by ultrasonic atomization. We show experimental data and propose a conceptual mechanism for the ultrasonic separation of metal ions.     

混合稀土离子的毛细管电泳电导法分离检测

采用高效毛细管电泳电导检测法分离检测了稀土离子。以醋酸-醋酸钠为背景电解质,4-吗啉乙磺酸（MES）为络合剂,在24kV的高压下,7种稀土离子得到子较好的分离。考察了背景电解质的pH和浓度,络合剂的浓度,分离电压等对稀土离子分离的影响。在选定的实验条件下,7种烯土离子在10min内守成分离检测。     

Separation of metal ions on a modified aluminium oxide

The possibility of application of a sulpho-derivative of an aromatic organic complexing agent for separation of cations on aluminium oxide has been investigated. Alumina modified with Nitroso-R salt is used for recovery of cobalt from a tap water and for selective separation of palladium from rhodium.     

Amorphous molybdenum sulfide mediated EDTA with multiple active sites to boost heavy metal ions removal

The rational design of strong affinity adsorbents for heavy metal ions removal remains a critical challenge for water treatment. In this study, amorphous molybdenum sulfide composites (EDTA-MoS_x (x = 2, 3)) were fabricated via a facile hydrothermal method mediated by EDTA, which was applied to heavy metal ions (Cu²⁺, Cd²⁺, Pb²⁺, Zn²⁺ and Ni²⁺) removal from aqueous solutions. A case study for Cu²⁺ ions showed that the adsorption capacity of EDTA-MoS_x (x = 2, 3) was superior to crystalline phase MoS₂ at pH 6.0 with an initial concentration of 200 mg/L. Adsorption mechanisms of different sulfide groups and COOH of EDTA-MoS_x (x = 2, 3) were verified systematically via a series of experiments, characterizations, and density functional theory (DFT) calculations. Both bridging S₂²⁻ and COOH covalently bonded with Cu²⁺ ions were ascribed to the critical factors for this enhanced removal efficiency on the surface of EDTA-MoS_x (x = 2, 3). This work offers a new method to enhance the adsorption performance of molybdenum sulfide-based materials by controlling crystallinity mediated with an organic complex small molecule.     

Separation and evaluation of soybean protein hydrolysates prepared by immobilized metal ion affinity chromatography with different metal ions

Metal ion affinity chromatography is widely used to purify peptides on the basis of the dissimilarities of their amino acids. However, researchers are interested in the separation differences between different metal ions in this method. In our study, four kinds of commonly used metal ions are compared by the amount of immobilized metal ion on iminodiacetic acid-Sepharose and binding amount of soybean peptide to immobilized iminodiacetic acid-Mn(+) adsorbents and evaluated by high-performance liquid chromatography (HPLC) profiles. The results show that due to the different adsorption behaviors of metal ions, the binding ability order of soybean protein peptide on the column should be Fe(3+) > Cu(2+) > Zn(2+) > Ca(2+). The HPLC profiles show that peptides adsorbed by four kinds of metal ions display similar strong hydrophobic characteristics.     

Separation of metal ions and metal-containing species by micellar electrokinetic capillary chromatography, including utilisation of metal ions in separations of other species

The use of micellar electrokinetic capillary chromatography (MEKC) for the separation of metal ions and metal-containing species is reviewed, together with the use of metal ions as a means to separate other species. Topics covered include the manipulation of separation selectivity through the use of complexation reactions induced by addition of a metal ion to the background electrolyte, enantiomeric separations facilitated through metal-analyte interactions, separation of organometallic species, separation of stable metal complexes in which the entire complex is the analyte and the separation of metal ions as analytes using pre-capillary or on-capillary complexation reactions with a suitable ligand.     

Separation of metal ions on tin(iv) tungstate and selenite papers

Papers impregnated with the inorganic ion-exchangers tin(IV) tungstate and selenite have been shown to be useful for ion-exchange chromatography of several metal ion mixtures, and suitable solvent systems have been developed and evaluated.     

Separation of metal ions via capillary electrophoresis using a pseudostationary phase microfunctionalized with carbon nanotubes

Microchimica Acta - This study reports on the use of dispersed multi-walled carbon nanotubes (MWCNTs) as a novel pseudostationary phase in capillary electrophoresis for the separation and...     

催化滴定 III: 影响EDTA滴定金属离子时突跃的因素

本文探讨以催化反应指示终点直接用EDTA滴定金属离子时影响突跃的因素. 采用滴定曲线突跃部分的斜率, tanθ, 作为指示反应速率的表征. 通过实验探讨了PH、CuEDTA和NiTrien用量以及滴定速率对tanθ的影响, 并从理论上导出tanθ的近似表达式, 它是NiTrien的起始浓度、加入EDTA的速率以及EDTA与NiTrien的反应速率常数三个变量的线性函数, 利用这一表达式可对实验结果作出较为满意的解释.