ABSTRACT
Recently, the problem of food security is more and more serious, and people pay attention to mercury because of the toxic of it. A new approach for the determination of mercury content in foodstuff is devised. In this paper, first, we design and synthesis a new kind of fluorescent probe whose matrix based on rhodamine B, hydrazine hydrate and hydroxy benzaldehyde. Through the analysis of H-NMR spectra of the synthesized product L1, we confirm that the synthetic substance is the adjacent carboxyl benzaldehyde hydrazone structure generation of rhodamine B. Then, we measure the fluorescence signal intensity of the probe with different concentrations of mercury ions fully upon complexation by fluorescence spectrometer and we can study the relationship between the mercury ion concentration and the fluorescence intensity and draw the standard working curve. Following, It's time to discuss the microwave digestion processing of tea, after digestion we use the synthetic probe Li for determination of mercury content in tea. The experimental results show that the maximum excitation wavelength of the probe and coordination compound are 568. 05 and 560. 00 nm, the maximum emission wavelength are 587. 94 and 580. 00 nm. Then we can find the best testing conditions to improve the degree of accuracy, that is: room temperature, 50% the methanol solution, 3. 0 mL pH 4. 0 buffer solution, in the extent of 30 min. The experimental results show that Na+, K+, Ca2+, Cu2+, Zn2+, Al3+ have little impact on the fluorescence intensity of the:probe. Fe3+, Mg2+, Ba2+ has a weak enhancement to the fluorescence intensity of the probe. While a low concentrations of Hg2+ have an obviously enhanced effect on the fluorescence intensity of the probe. In contrast to other metal ions, the probe for Hg2+ has a good selectivity. Linear relationship between the magnitude of increase in fluorescence intensity and concentration of mercury ion was in the range of 5~20 ng . L-1 with detection limit (3S/N) of 1. 9 ng . L-1. The proposed method was applied to determination of mercury ion in samples of tea and sausage and the obtained result and sample recovery were all satisfactory. The methods of analysis instrument has the advantages of simple structure, sensitivity, high accuracy, good selectivity and less volume of simple, without the need for enrichment, being very practical.
Subject(s)
Fluorescent Dyes/chemistry , Food Analysis/methods , Mercury/analysis , Rhodamines/chemistry , Spectrometry, Fluorescence , Buffers , Hydrogen-Ion Concentration , Ions , Limit of DetectionABSTRACT
In the title compound, [Cu(C(4)HN(3)O(4))(H(2)O)(3)](2)[Cu(2)(C(4)HN(3)O(4))(2)(H(2)O)(6)], both monomeric and dimeric mol-ecules are present in the solid state. In the monomeric compound, the Cu(II) atom is five-coordinated in a square-pyramidal configuration by one O atom and one N atom from one 1H-1,2,4-triazole-3,5-dicarboxyl-ate (TZDCA(2-)) ligand and three O atoms from water mol-ecules. In the centrosymmetric binuclear complex, each Cu(II) atom is six-coordinated in an octa-hedral geometry by one O atom and one N atom from one TZDCA(2-) ligand and four O atoms from water mol-ecules, two of which bridge the Cu(II) atoms. In the structure, there are intra-molecular O-Hâ¯O and N-Hâ¯O hydrogen bonds, and in the crystal, inter-molecular O-Hâ¯O, O-Hâ¯N and N-Hâ¯O hydrogen bonds link symmetry-related mol-ecules, forming a three-dimensional supra-molecular structure.
ABSTRACT
The unique behavior of a new Ru(II) diimine complex, Ru(bpy)(2)(L)(2+) (where L is 4-methyl-4'-[p-(dimethyl- amino)-alpha-styryl]-2,2'-bipyridine, bpy is 2,2'-bipyridine), was studied in detail. Due to the strong electron donating property of the amino group, an ILCT (intraligand charge transfer) state is involved either in the absorption spectra or in the time-resolved emission spectra. Dual emission based on (3)MLCT and (3)ILCT states was observed at room temperature for the first time via a time-resolved technique in Ru(II) diimine complexes.
