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101.
A study of the mechanisms involved in the separation of metal ions with a mixed-bed stationary phase
Summary The optimization of chromatographic methods for the determination of metal species require an understanding of the mechanisms
involved. In this work, the separation of Cd, Co, Cu, Fe(II/III), Mn, Pb and Zn using a mixed bed column (IonPac CS5A) and
a cation-exchange column (IonPac CS2) is studied as a function of mobile phase composition. The type and concentration of
complexing agent and of ionic strength modificators were evaluated. The charge of analytes were calculated using the classical
ion exchange approach to highlight the effect of eluent composition on retention. The comparative study enabled us to identify
an optimal eluent composition for the separation of the nine metal species. 相似文献
102.
103.
Jorge Macanás 《Analytica chimica acta》2005,534(1):101-108
Activated composite membranes (ACMs) containing di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier have been found to facilitate the transport and separation of several cations. This paper describes an approach to the chemical characterisation of the transport phenomena of Zn2+, Cd2+, Cu2+, Ni2+, Sn2+ and In3+ by an ACM. The selectivity of D2EHDTPA based ACM towards different metal ions is presented and discussed focusing in Zn2+ and Cd2+ transport and recovery. Selectivity demonstrates that zinc ions are removable from mixtures due to the different extraction strength of D2EHDTPA. Such selectivity is based on the differences of the dynamic behaviour of the metal ions transport. In addition, a correlation of the chemical behaviour of those ACM systems with the corresponding solvent extraction systems has been found. 相似文献
104.
CHEN Kai ZHU Zhong-liang ZHANG De-jun 《高等学校化学研究》2006,22(4):435-438
IntroductionStudies on reversible kinetic systems are consi-dered as a hotspot of chemical and biochemical kineticresearches[1,2]. Of late, some researches have been fo-cused on the simultaneous optimization of the obverseand reverse rate constants[3,4].H… 相似文献
105.
Summary. A new polymeric resin with sulfonamide pendant functions has been prepared for the selective extraction of mercuric ions.
This polystyrene sulfonamide urea resin with a 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from
aqueous solutions. The mercury sorption capacity of the resin is around 1.60 mmol/g under non-buffered conditions. The experiments
performed under identical conditions with some metal ions reveal that Cd(II), Pb(II), Zn(II), and Fe(III) ions are also extractable
in low quantity (0.05–0.1 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid without hydrolysis
of the amide groups. 相似文献
106.
Fa-Kun Zheng A-Qing Wu Yan Li Guo-Cong Guo Ming-Sheng Wang Qiang Li Jin-Shun Huang 《Journal of Molecular Structure》2005,740(1-3):147-151
Three new metal complexes, Cu(4-Hcba)2(4-cba)2(Py)2 (4-Hcba=4-cyanobenzoic acid) 1 and M[H(4-cba)2]2(Py)2 (M=Ni 2, Co 3), have been prepared by the treatment of 4-Hcba with the respective metal nitrate M(NO3)2 (M=Cu, Ni, Co) in the presence of pyridine (Py). Single-crystal X-ray diffraction analyses (3 is isostructural to 2) show that the obtained complexes are of isolated mononuclear and the metal atoms have distorted octahedral coordination environment. Two different types of intramolecular hydrogen bonds exist: asymmetrical O–HO for 1 and symmetrical OHO for 2 and 3. The crystal packing between the molecular complexes is controlled mainly by T-shaped C–Hπ interactions between pyridine and phenyl rings. Preliminary discussions on IR, UV–VIS and fluorescent spectra have also been carried out. 相似文献
107.
A pyrene-functional fluoroionophore, 1 was used to construct a supramolecular 1/γ-CD complex for Cu2+ recognition in water. In aqueous γ-CD solution, 1 exhibits pyrene monomer fluorescence emission at 378 nm and 397 nm, while in the presence of Cu2+, it shows a pyrene excimer emission at 452 nm with a decrease in the monomer fluorescence due to the formation of a 1:2 metal-liganded complex. Based on the response characteristics of the supramolecular complex, a fluorescent ratiometric method was performed for the determination of Cu2+ concentration in water. With the optimum conditions described, Cu2+ in aqueous solution can be determined from 1.2 × 10−6 to 4.5 × 10−4 M. The Cu2+ selectivity of the complex is excellent, and the excimer fluorescence enhancements are very smaller induced by other heavy metal and transition metal ions. 相似文献
108.
2-{[1-(3,4-Dihydroxyphenyl)methylidene]amino}benzoic acid (DMABA) was loaded on Amberlite XAD-16 (AXAD-16) via azo linker and the resulting resin AXAD-16-DMABA explored for enrichment of Zn(II), Mn(II), Ni(II), Pb(II), Cd(II), Cu(II), Fe(III) and Co(II). The optimum pH values for extraction are 6.5-7.0, 5.0-6.0, 5.5-7.5, 5.0-6.5, 6.5-8.0, 5.5-7.0, 4.0-5.0 and 6.0-7.0, respectively. The sorption capacity was found between 97 and 515 μmol g−1 and the preconcentration factors from 100 to 450. Tolerance limits for foreign species are reported. The kinetics of sorption is fast as t1/2 is ≤5 min. The chelating resin can be reused for 50 cycles of sorption-desorption without any significant change (<1.5%) in the sorption capacity. The limit of detection values (blank +3 s) are 1.12, 1.38, 1.76, 0.67, 0.77, 2.52, 5.92 and 1.08 μg L−1 for Zn(II), Mn(II), Ni(II), Pb(II), Cd(II), Cu(II), Fe(III) and Co(II), respectively. The enrichment on AXAD-16-DMABA coupled with monitoring by flame atomic absorption spectrometry (FAAS) is used to determine all the metal ion ions in river and synthetic water samples, Co in vitamin tablets and Zn in milk samples. 相似文献
109.
Tsutomu Takeichi Hiroshi Yada Yuzi Takayama Masami Morikawa 《Journal of separation science》1995,18(10):630-634
A chiral stationary phase prepared by bonding L -valine-t-butylamide to XE-60 has been coated on glass and metal capillaries. The performances of the chiral glass and metal columns were equivalent to those of commercial fused silica capillary columns. The thermal stability of the glass column was examined up to 280°C. It was found that no appreciable change in separation factor (α value) was observed up to 230°C. The α values gradually decreased between 240 and 260°C, and enantiomer separation was no longer achieved at 280°C. It was concluded that the allowable upper limit temperature of the chiral stationary phase is between 230 and 240°C in the isothermal mode, and ca 260°C in temperature-programmed mode. 相似文献
110.