Effects of various competing ligands on the kinetics of trace metal complexes of Laurentian Fulvic Acid in model solutions and natural waters

The objective of this work was to study the effects of the following Ligands: Chelex-100, Dowex MAC-3 and Dowex 50WX-8 using Competing Ligand Exchange Method. This objective was achieved by investigating complex dissociation kinetics of trace metals: Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Mn(II) and Pb(II) of a well-characterized Laurentian Fulvic Acid (LFA) in model solutions and in a natural waters of Lake Heva (Québec, Canada). The effects of variation in the competing ligands (including their quantities) on the complex dissociation kinetics were quantitatively characterized by their first-order dissociation rate coefficients. The kinetic lability of the metal complexes varied with the metal-to-LFA ratio, as expected from the theory of metal complexes of the chemically and physically heterogeneous complexants, LFA. The general trend in the metal-binding by the above competing ligands was: Dowex 50WX-8 > Chelex-100 > Dowex MAC-3. However, no difference was found between the Dowex 50WX-8 and Chelex-100 for Cd(II), Zn(II), and Co(II). The results revealed the importance of the quantity of Chelex-100 as a competing ligand in the metal(II)-LFA complexation, on the dissociation kinetics of these complexes in model solutions. By developing Competing Ligand Exchange Method as an analytical technique, for studying the relative affinities of the above competing ligands for metals complexation in natural waters this work has made a substantial contribution to analytical chemistry.     

A solid phase extraction using a chelate resin immobilizing carboxymethylated pentaethylenehexamine for separation and preconcentration of trace elements in water samples

A chelate resin immobilizing carboxymethylated pentaethylenehexamine (CM-PEHA resin) was prepared, and the potential for the separation and preconcentration of trace elements in water samples was evaluated through the adsorption/elution test for 62 elements. The CM-PEHA resin could quantitatively recover various elements, including Ag, Cd, Co, Cu, Fe, Ni, Pb, Ti, U, and Zn, and rare earth elements over a wide pH range, and also Mn at pH above 5 and V and Mo at pH below 7. This resin could also effectively remove major elements, such as alkali and alkaline earth elements, under acidic and neutral conditions. Solid phase extraction using the CM-PEHA resin was applicable to the determination of 10 trace elements, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn, in certified reference materials (EnviroMAT EU-L-1 wastewater and ES-L-1 ground water) and treated wastewater and all elements except for Mn in surface seawater using inductively coupled plasma atomic emission spectrometry. The detection limits, defined as 3 times the standard deviation for the procedural blank using 500 mL of purified water (50-fold preconcentration, n = 8), ranged from 0.003 μg L⁻¹ (Mn) to 0.28 μg L⁻¹ (Zn) as the concentration in 500 mL of solution.     

Inductively coupled plasma atomic emission spectrometric determination of 27 trace elements in table salts after coprecipitation with indium phosphate

The coprecipitation method using indium phosphate as a new coprecipitant has been developed for the separation of trace elements in table salts prior to their determination using inductively coupled plasma atomic emission spectrometry (ICP-AES). Indium phosphate could quantitatively coprecipitate 27 trace elements, namely, Be, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, in a table salt solution at pH 10. The rapid coprecipitation technique, in which complete recovery of the precipitate was not required in the precipitate-separation process, was completely applicable, and, therefore, the operation for the coprecipitation was quite simple. The coprecipitated elements could be determined accurately and precisely by ICP-AES using indium as an internal standard element after dissolution of the precipitate with 5 mL of 1 mol L⁻¹ nitric acid. The detection limits (three times the standard deviation of the blank values, n = 10) ranged from 0.001 μg (Lu) to 0.11 μg (Zn) in 300 mL of a 10% (w/v) table salt solution. The method proposed here could be applied to the analyses of commercially available table salts.     

Detection of Trace Heavy Metals Ions by Arrays of Titania Nanotubes Annealed in Nitrogen

Redox response of trace heavy metals ions(THMIs) has better performance on highly ordered vertically oriented titania nanotube arrays(TNA) annealed in nitrogen. Experimental data showed that different THMIs possess different reaction peak shapes and charge and discharge capacities. Therefore, the TNA will become an important tool used for environmental protection and facilitating the rapid determination of THMIs. THMIs of 5×10-4 mol/L concentration were measured at a scan rate of 100 mV/s. The analytical ut...     

金花茶花朵中微量元素的研究

对金花茶花朵不同部位微量元素的含量进行了分析研究.采用微波消解样品,电感耦合等离子体原子发射光谱法同时测定钾、钠、钙、镁、磷、铜、铁、锌、锰、钼、镍、铅、镉、铬的含量.结果表明,花朵中富含微量元素,且而各元素含量在花瓣、花蕊、花粉之中差异较大,为进一步开发金花茶的花朵提供依据.     

Polyallylammonium Ferrocyanide Films for Trace Water Detection in Halogenated Solvents

Polyallylammonium films with electrostatically bound ferrocyanide were formed by electrochemically reducing ferricyanide ions in the presence of polyallylammonium chloride. These films could be deposited onto the surfaces of Pt, Au or SnO₂ electrodes. In anhydrous organic electrolyte solutions, these films are electroinactive but become electroactive after the addition of trace water. For concentrations of water from 0.0 to 0.12% in chlorinated solvents, the electroactivity is linear with water concentration. The linearity between concentration of water and electroactivity can be exploited to develop a subsaturation trace water sensor.     

Novel Sensitive Voltammetric Detection of Trace Gallium(III) with Presence of Catechol Using Mercury Film Silver Based Electrode

A new adsorptive stripping voltammetric method for the determination of trace gallium(III) based on the adsorption of gallium(III)‐catechol complex on the cyclic renewable mercury film silver based electrode (Hg(Ag)FE) is presented. The effects of various factors such as: preconcentration potential and time, pulse height, step potential and supporting electrolyte composition are optimized. The calibration graph is linear from 2 nM (0.14 μg L^?1) to 100 nM (6.97 μg L^?1) for a preconcentration time of 30 s, with correlation coefficient of 0.9993. For a Hg(Ag)FE with a surface area of 9.7 mm² the detection limit for a preconcentration time of 90 s is as low as 7 ng L^?1. The repeatability of the method at a concentration level of the analyte as low as 0.05 μg L^?1, expressed as RSD is 3.6% (n=5). The proposed method was successfully applied by studying the natural samples and simultaneous recovery of Ga(III) from spiked water and sediment samples.     

Studies on the full vibrational energies and dissociation energies of some heteronuclear diatomic molecules

A parameter-free analytical formula for dissociation energies of diatomic molecules is proposed by Fan and Sun (2009) [20] based on LeRoy and Bernstein's vibrational energy expression near dissociation limit. Using three highest vibrational energies which may be generated by the algebraic method (AM) presented in our previous study and by some other physical methods, the new formula is applied to study the molecular dissociation energies of 10 electronic states of KH, ⁷LiD, ⁷LiH, ⁶LiH, NaK, NaLI and NaRb heteronuclear diatomic molecules which have regular (Morse-like) potentials in this work. The results show that the AM energies and dissociation energies have excellent agreement with experimental values.     

Some number-theoretic identities from group actions

We apply group actions to some natural situations like the natural ‘linear’ action of GL _r (Z _n ) and some of its subgroups to derive number-theoretic identities like