Metal Complexes Characteristics Of Thin-layer Chromatography And The Separation And Analysis Applications

With the aggravation of environmental pollution, people pay more attention to the analysis of the poisonous heavy metals ions in the environment. For the concentration of the metal ions in the environment are usually very low and the some kin metals are usually concomitant, many analytical methods applied to this realm are normally combining convenient and reliable separation and preconcentration with sensitive detection methods. Separation process has been performed using precipitation separation, solvent extraction, vaporization and distillation, membrane separation and polymeric syntheticresin for separation, and the detection methods include atom absorption spec-trometry, polarography, stripping voltammetry, plasma emission spectrometry and X-ray fluorescence spectrometry. Thin-layer chromatography is a simple and effective method of separating metal complexes, and it could be combined with many detection methods conveniently. In this paper after the chromatographic behavior of metal complexes were studied, many metal ions were analyzed using thin-layer chromatography separation and thin-layer chromatogram scan or atom absorption spectrometry detection. The major contents are described as follows:(1) The chromatographic behavior of some heavy metal such as Cu( II ) Co( II) and Ni(II) etc., on silica gel thin layers has been studied. The effect of ten developing agents and their mixed system on the Rf value of metal chelates were investigated. A series of good separation of the three metals have been achieved successfully and the influence rule of the Rf value following the polarity of developing agents was educed, the method has been applied to separate Cu( II )and Ni( II) in real sample in dual-developing agent — toluene/phenixin(V:V=1:1), and quantitative determination were obtained with graphite furnace atomic absorption spectrometry. The applicability of the proposed methodology in standard and lake water samples has been proved.(2) The chromatographic behavior of some heavy metal such as Co( II ) Ni( II) Cu(II)and Fe(II)on silica gel thin layers has been studied. The effect of several developing agents and their mixed system on the Rf value of metal chelates were studied. Good separation of the four metals have been achieved successfully .the method has beenapplied to separate Ni(II) and Cu(II)in standard sample and real sample with dual-developing agent-butanone/butyl acetate(V:V=l:l), and quantitative determination were achieved by thin layer chromatogram scanner in 560nm.(3) The chromatographic behavior of the complexes of some novel metals with heterocyclic azo compounds on silica gel thin layers has been studied. The complex of Pd(II) has been separated with other novel metals in ethyl acetate, and the effect of structure on the Rf value of Pd( II)-heterocyclic azo compounds has been discussed, quantitative determination were obtained with thin-layer chromatogram scan in 570nm, The method has been applied to analyze Pd( II )in water sample and the satisfied results were obtained.(4) The chromatographic behavior of the complexes of Fe( II )/Fe(IH) with 5-Br-PADAP on thin layer of silica gel was studied and separation of Fe(II)and Fe(IH)were obtained successfully, dual-developing agent-butanone/ methyl acetate(V:V=l:l)was selected to eliminate the interference of other metal ions. This method was applied to separate Fe( II) in real sample, then the sample was treated with VC to reduce Fe(III) into Fe( II), and quantitative determination of Fe( II) and total iron was successfully achieved by graphite furnace atomic absorption spectrometry and the concentration of Fe(III) was obtained by subtraction, and the detection limit of Fe( II) was 0.085μg.mL~-1.