Zeng Yun'e

Instrument for Hadamard transform three-dimensional fluorescence microscope image analysis

Abstract An instrument combining fluorescence microscopy with Hadamard transform multiplexed imaging was designed by which a three-dimensional Hadamard transform fluorescence microscopic cell image was obtained. The image can provide useful information including, simultaneously, the apparent dimensions and the shape of the analytical sample, the content and the distribution of some species in it.

Slurry sample introduction with fluorinating electrothermal vaporization for the direct ICP-AES determination of boron in plant leaves

The slurry sample introduction with fluorinating electrothermal vaporization has been applied to ICP-AES for the determination of boron in plant leaves. The main working parameters for ETV-ICP-AES, such as r.f. power, gas flow rate, drying temperature and atomization temperature have been studied. The concentration of the fluorinating agent polytetrafluoro-ethylene was examined for the boron determination. The matrix concentrations of Na, K, Ca and Mg up to 5 mg/ml do not interfere with the fluorinating vaporization of boron. Several plant samples were analysed with the standard addition method. A good agreement of analytical results between this method and a spectrophotometric method was obtained. The determined value of boron in NBS SRM 1573 tomato leaves coincides with literature values.SummaryThe slurry sample introduction with fluorinating electrothermal vaporization has been applied to ICP-AES for the determination of boron in plant leaves. The main working parameters for ETV-ICP-AES, such as r.f. power, gas flow rate, drying temperature and atomization temperature have been studied. The concentration of the fluorinating agent polytetrafluoro-ethylene was examined for the boron determination. The matrix concentrations of Na, K, Ca and Mg up to 5 mg/ml do not interfere with the fluorinating vaporization of boron. Several plant samples were analysed with the standard addition method. A good agreement of analytical results between this method and a spectrophotometric method was obtained. The determined value of boron in NBS SRM 1573 tomato leaves coincides with literature values.

Organic solvent enhanced spectrofluorimetric method for determination of laccase activity

A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenazine. The optimal conditions for laccase in organic media areT=55°C, pH=6.5, 1.0×10−2mol/L OPDA, 1.25 mL ethanol, 1.25 mL 1,4-dioxane and 1.25 mL acetone. The linear range of the method proposed in ethanol, 1,4-dioxane and acetone media were 0.44–19.33, 0.11–20.85, 0.38–21.05 U with the detection limit of 0.088, 0.022, 0.076 U, respectively. The proposed method has been applied to the analysis of laccase activity of real samples with more accurate and sensitive than that of the previous method reported.

Slurry sampling and fluorination–electrothermal vaporization inductively coupled plasma atomic emission spectrometry for the direct determination of molybdenum in food

A method for the direct determination of Mo in various types of food by fluorination–electrothermal vaporization inductively coupled plasma atomic emission spectrometry has been developed and optimized. Slurry samples were prepared by ultrasonic wave vibration, after pre-treatment and direct injection into the graphite furnace using polytetrafluoroethylene as a fluorinating agent. The procedure was applied to the determination of Mo in National Institute of Standards and Technology Standard Reference Materials 1567 Wheat Flour, 1568 Rice Flour and 1577 Bovine Liver. The values found were in reasonable agreement with the certified values, with a detection limit of 0.7 ng ml–1 and an RSD of 3.2%(n= 10) at a concentration of 0.1 µg ml–1. The proposed procedure has been applied successfully to the analysis of various types of food samples; the recovery ranged between 92 and 105%.

Direct determination of aluminium in biological materials by electrothermal vaporization-inductively coupled plasma atomic emission spectrometry with polytetrafluoroethylene as chemical modifier

Abstract A method for the determination of aluminium in biological materials with electrothermal vaporization and inductively coupled plasma atomic emission spectrometry is described, in which polytetrafluoroethylene (PTFE) is used as chemical modifier to improve the vaporization of aluminium. The absolute detection limit of aluminium is 5.0 pg and the R.S.D. is 2.2% at an aluminium concentration of 0.2 μg ml−1 (n = 9). The reliability of the entire procedure was confirmed by analyses performed on three standard reference biological materials.

The application of multiwavelength spectrophotometry to the analysis of rare earths

Abstract Dual- and three-wavelength spectrophotometry methods are very useful. We have applied them to the analysis of two-component mixtures of rare earths by a method involving the formation of new asymmetrical bisazo derivatives of chromatropic acid.

Chemiluminescence determination of thiourea using tris (1,10-phenanthroline)-ruthenium (II) KMnO4 system

The light emission produced by thiourea in oxidation process by permanganate in acidic solution in the presence of Ru(phen)23+ is used to determine 1.0×10−5 −1.0×10−5 mol/L thiourea. The limit of detection is 9.8×10−9 mol/L and the relative standard deviation is 1.1% for a 1.0×10−5 mol/L thiourea solution (n=10). The method was applied satisfactorily to the determination of thiourea.

The effect of laser irradiation on surface enhanced raman scattering for silver film

The laser irradiation effect on the SERS intensity for Ag film is discussed using crystal violet (CV) as a probe. The thickness of silver film, the etching time of the glass slide by gaseous hydrogen fluoride, and the laser irradiation time for different amounts of CV on silver films were investigated. The laser burn-out model was proposed to explain the dependence of the SERS intensity of CV on the laser irradiation time.

Simultaneous determination of Dy, Eu, Sm and Tb by laser induced-time resolved derivative fluorescence

In this paper, a highly sensitive laser fluorimetric system coupled with microcomputer is described and the laser induced fluorescence of ternary complexes formed by RE (RE = Dy, Eu, Sm, and Tb) with TFA (Trifluoroacetylacetone) and TOPO (Trioctylphosphine oxide) is studied. The emission spectra (excited at 310 nm) of the TFA/TOPO complexes of the rare earths show that the strongest emission bands are located at 560 nm for Dy, 614 nm for Eu, 644 nm for Sm, and 544 nm for Tb. Thus, it is preferable to establish the detection at these wavelengths. However, it is difficult to detect one single component with high selectivity in a mixed sample, because the emission bands in the 500–700 nm region overlap. In order to improve the selectivity, time resolved and derivative techniques are introduced. The effects of foreign ions on the determinations of these four elements are investigated. The linear relationships between derivatives and the concentrations of Dy, Eu, Sm, and Tb are 5×10−8 to 5×10−6 mol/l, 5×10−10 to 1×10−7 mol/l, 1×10−9 to 2×10−6 mol/l, and 2×10−9 to 2×10−6 mol/l, respectively. The method was used to determine simultaneously the amounts of Dy, Eu, Sm, and Tb in their mixtures and yttrium oxide without pre-separation.SummaryIn this paper, a highly sensitive laser fluorimetric system coupled with microcomputer is described and the laser induced fluorescence of ternary complexes formed by RE (RE = Dy, Eu, Sm, and Tb) with TFA (Trifluoroacetylacetone) and TOPO (Trioctylphosphine oxide) is studied. The emission spectra (excited at 310 nm) of the TFA/TOPO complexes of the rare earths show that the strongest emission bands are located at 560 nm for Dy, 614 nm for Eu, 644 nm for Sm, and 544 nm for Tb. Thus, it is preferable to establish the detection at these wavelengths. However, it is difficult to detect one single component with high selectivity in a mixed sample, because the emission bands in the 500–700 nm region overlap. In order to improve the selectivity, time resolved and derivative techniques are introduced. The effects of foreign ions on the determinations of these four elements are investigated. The linear relationships between derivatives and the concentrations of Dy, Eu, Sm, and Tb are 5×10−8 to 5×10−6 mol/l, 5×10−10 to 1×10−7 mol/l, 1×10−9 to 2×10−6 mol/l, and 2×10−9 to 2×10−6 mol/l, respectively. The method was used to determine simultaneously the amounts of Dy, Eu, Sm, and Tb in their mixtures and yttrium oxide without pre-separation.

Continuous free focusing electrophoresis of metal ions in a stepwise gradient system of complexing agent

Abstract Theoretical considerations indicated the possibility of the focusing electrophoretic separation of metal ions using a stepwise gradient of complexing agent concentration. Separations of cations in several prepared samples were performed in an apparatus for continuous free electrophoresis. The separation performance and focusing effect of this system predicted theoretically were confirmed. Each component seeks its own concentration step in the completing agent.