Detection Of Uranium Copper And Zinc By Emission Spectrometry Based On Pyridoxal 5-phosphate-type Schiff Base Complexes

It is important to determine the contents of uranium, copper, and zinc because they are closely related to environment and human health. Therefore, in this paper, three new Schiff bases, N,N’-bis(pyridoxalphosphate)-o-phenylenediamine(BPPP), N,N’-bis(pyridoxal phosphate)-o- tetramino biphenyl(BPPB) and bis-phenanthroline-glutaraldehyde(BPG), were synthesized. By using these Schiff bases, three new analytical methods were developed for determination of uranium, copper and zinc, respectively. The methods are a resonance light scattering(RLS) method for the determination of uranium based on its coordination reaction with BPPP to form a supramolecular polymer, a fluorescence quenching method for the determination of copper based on its quenching effect on the fluorescence of BPPP, and a RLS method for the determination of zinc based on its coordination reaction with both BPPB and BPG to form a supramolecular polymer. These methods provide new strategy for the determination of uranium, copper and zinc.In the first part, at fist, research development of the methods for uranium, copper, and zinc detection were outlined. Then the research and application development of schiff base especially the schiff base containing Pyridoxal 5-phosphate were introduced. The application of coordination supramolecularpolymer as well as the principle and application of resonance light scattering were also summarized.In the second part, the new Schiff base BPPP was synthesized by utilizing the Schiff base condensation reaction of pyridoxal 5-phosphate with 1,2-Phenylenediamine. BPPP contains a tetradentate ligand and two phosphate groups. It can chelate uranyl and then self-assemble to form a supramolecular polymer, resulting in a production of strong RLS signal. The RLS method was established based on this fact. The linear range is 0.5~25 ng/m L with a detection limit of 0.2 ng/m L. The method is simple and has been successfully applied to determine uranium(VI) in environmental water samples.In the third part, the study on the detection of copper in foodstuffs by using BPPP as fluorescence probe was introduced. BPPP has the properties of high fluorescence stability, good water solubility and low toxicity. Its maximum excitation wavelength and maximum fluorescence emission wavelength are at 389 and 448 nm, respectively. When BPPP coexists with copper(II), its fluorescence is dramatically quenched. Under a certain condition, the fluorescence intensity decreased proportionally to the concentration of copper(II) by the quenching effect. Based on this fact, we established a fluorescence quenching method for the determination of copper(II). Under optimal conditions a linear range was found to be 0.5 to 50 ng/m L with a detection limit of 0.2 ng/m L. The method has been applied to determine copper(II) in foodstuff samples with satisfactory analytical results.In the forth part, BPPB was synthesized by utilizing the Schiff base condensation reaction of pyridoxal 5-phosphate with 3,3’,4,4’-tetraminobiphenyl. BPG was also synthesized with 1,10-phenanthrolin-5-amine and glutaraldehyde. BPPB is a ditopic tetradentate Schiff base ligand containing four phosphate groups and BPG is a ditopic bidentate ligand. Both BPPB and BPG can chelate zinc(II) together and then self-assemble to form a supramolecular polymer, resulting in the production of strong RLS signal. The amount of zinc was detected by measuring the RLS intensity. Under optimal conditions, a linear range was found to be 0.3~30 ng/m L with a detection limit of 0.1 ng/m L. The method has been successfully applied to determine zinc in infant milk powder samples with recoveries of 95~105%.