Publications (8)3.09 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: Based on their similarity in chemical properties, rare earth elements were able to form stable coordinated compounds with arsenazo III which were extractable into butanol in the presence of diphenylguanidine. The butanol was removed under reduced pressure distillation; the residue was dissolved with diluted hydrochloric acid. As was released with the assistance of KMnO4 and determined by hydrogen generation-atomic fluorescence spectrometry in terms of rare earth elements. When cesium sulfate worked as standard solution, extraction conditions, KMnO4 amount, distillation temperature, arsenazo III amount, interfering ions, etc were optimized. The accuracy and precision of the method were validated using national standard certified materials, showing a good agreement. Under optimum condition, the linear relationship located in 0.2-25 microg x mL(-1) and detection limit was 0.44 microg x mL(-1). After the herbal samples were digested with nitric acid and hydrogen peroxide, the rare earth elements were determined by this method, showing satisfactory results with relative standard deviation of 1.3%-2.5%, and recoveries of 94.4%-106.0%. The method showed the merits of convenience and rapidness, simple instrumentation and high accuracy. With the rare earths enriched into organic phase, the separation of analytes from matrix was accomplished, which eliminated the interference. With the residue dissolved by diluted hydrochloric acid after the solvent was removed, aqueous sample introduction eliminated the impact of organic phase on the tubing connected to pneumatic pump.
- [Show abstract] [Hide abstract] ABSTRACT: In the medium of 3 mol x L(-1) hydrochloric acid, Cr(VI) oxidized As(III) to be As(V), the As(III) content, which was left over, was determined by hydride generation-fluorescence spectrometry, giving that it was inversely proportional to Cr(VI) content. Based on the same principle and combined with potassium permanganate oxidation of Cr(III) to be Cr(VI), the Cr(III) was, therefore, determined. The sample digestion procedures and co-existing ions which might have interference were investigated. The instrumental operation parameters, reaction acidity and other influence factors were studied. Under optimum operation conditions, a good linear relationship was obtained in the range of 4.0-20 microg x L(-1) Cr. The detection limit of the method was 2.5 microg x L(-1). When the method was applied to milk analysis, a relative standard deviation (RSD, n = 6) of 1.6%-2.7% was found. The recovery was 96.5%-104.2%.
- [Show abstract] [Hide abstract] ABSTRACT: After dissolved in HNO3-HClO4 and the copper matrix was masked with a new nontoxic, pollution free and environment friendly reagent-polyepoxysuccinic acid, the selenium in the brass sample was directly determined without any separation procedures. The method was simple, rapid, accurate, precise and low cost operation. The linear dynamic calibration was 5.0-80.0 mu g/L. The detection limit of the method was 0.29 mu g/L. The relative standard deviation (RSD, n=11) was 2.4%. The recovery rate with standard addition was 97.5%-104.8%.
- [Show abstract] [Hide abstract] ABSTRACT: A method for the determination of iodine based upon compound H2HgI4, formed between I− and Hg2+ in nitric acid and extracted in methyl isobutyl ketone(MIBK), was developed via atomic fluorescence spectrometry(AFS). After the compound is reduced with potassium borohydrid(KBH4), the resultant mercury vapor was injected into the instrument and iodine was, therefore, indirectly determined. Experimental parameters such as the conditions of extraction reagents, aqueous phase acidity, elemental mercury diffusion temperature in a vial and other factors were investigated and optimized. Under the optimum experimental conditions, this method shows a detection limit of 0.038 μg/L iodine and a linear relationship between 0.04–20 μg/L. The method was applied to determining the iodine content in marine duck eggs, kelps, laver and Ganoderma lucidum spirulina, showing a relative standard deviation(RSD) of 2.15% and the recoveries in the range of 98.1%–102.5%.
- [Show abstract] [Hide abstract] ABSTRACT: Using La2O3, Dy2O3, NH4VO3, HNO3 as materials, solvothermal synthesis method was adopted to prepare LaVO4 : Dy3+ nanorods through adjusting the pH values of ethanol-water mixing solution. The as-prepared samples were characterized by X-ray diffraction, transmission electron microscope, infrared spectrum, UV-Vis absorption spectra and fluorescence spectra. The results show that the phase transition from m- to t -LaVO4 : Dy3+ can be found when the pH value changes from 2 to 4. With the increase of the pH value of the mixing solution, the grain size of the sample becomes smaller and the shape of LaVO4 : Dy3+ crystal changes from irregular nanoparticle to one dimension nanorod. Besides, the band gap of the sample decrease from 3.68 (pH 2) to 3.43 eV (pH 10). It is found from FL that the excitation spectra of LaVO4 : Dy3+ nanorods have a little red shift in comparison with irregular nanoparticle. Furthermore, the LaVO4 : Dy3+ nanorod exhibits the strongest yellow emission (4F9/2-6 H13/2) and blue emission(4F9/2-6H15/2), and it possesses the largest Y/B value (1.039).
- [Show abstract] [Hide abstract] ABSTRACT: A method for indirectly determining the molybdenum in Chinese herbal medicine by butanol extraction and dilute hydrochloric acid dissolution was established for atomic fluorescence spectrometry. The molybdoarsenate heteropoly acid, formed in the presence of As(V) and ammonium molybdate in 0.3 mol x L(-1) sulphuric acid medium, was separated and enriched in the organic solvent, then the evaporation of organic reagent was implemented and the left residue was dissolved in dilute hydrochloric acid in which the arsenic content was determined on behalf of molybdenum. In the optimum experimental conditions, molybdenum content in 0-15 microg x L(-1) range depicts a good linear relationship, the detection limit and relative standard deviation of 0.44 microg x L(-1) and 1.1% were obtained, respectively. Spiked Chinese herbal medicine samples were determined with the proposed method, and recoveries of 95.6%-101.3% were achieved.
- [Show abstract] [Hide abstract] ABSTRACT: In this paper, a new method was developed for indirect determination of iodine with methyl isobutyl ketone (MIBK) extraction by atomic fluorescence spectrometer (AFS). Based upon the complex, which can be extacted perfectly by MIBK, formed between I- and Hg2+ in 0.1 mol x L(-1) of nitric acid, indirectly measuring the iodine in organic phase becomes possible. The effects of extraction conditions and other influence factors were investigated. Under the optimized experimental conditions, the results showed that the linearity between its absorbance and the concentration of iodine was 0-12 microg x L(-1), the detection limit is 0.14 microg x L(-1), and the relative standard deviation is 3.3%. The method has been applied to the determination of iodine in eggs, and the recoveries are in the range of 101.8%-110.4%.
- [Show abstract] [Hide abstract] ABSTRACT: Volatile oil was extracted from star anise seeds or shell using hexane with the aid of microwave. The optimal extraction process determined using orthogonal array design was based on 640 W microwave treatment for 5 min with a material/liquid ratio of 1:1.5. Compared with traditional extraction methods, microwave-assisted n-hexane extraction had characteristics of high efficiency, fast speed and energy-saving. Meanwhile, the analysis of fatty acids in anise seed oil revealed similar compositions with commercially available vegetable oil. Therefore, refined anise seed oil was qualified to be edible according to requirements for human consumption. Furthermore, fatty acids in anise seed shell oil were relatively lower than other edible oils, which made it as an excellent material for fragrance and flavor ingredients.
Yung-ning, Guangxi Zhuangzu Zizhiqu, China
- School of Chemistry and Chemical Engineering