Atomic fluorescence spectrometry with laser excitation

A laser atomic fluorescence spectrometry for the detection of trace concentrations of the elements is described. The detection limits for Pb, Fe, Na, Pt, Ir, Eu, Cu, Ag, Co and Mn in aqueous solutions obtained at present are the best ones for the rapid spectral analytical methods. The analytical potentials of the laser spectrometer are exemplified by the analysis of real samples of different chemical composition.     

Atomic and ionic fluorescence spectrometry with pulsed dye laser excitation in the inductively-coupled plasma

The atomic and ionic fluorescences of iron, tin, barium and indium excited by flash-lamp-and nitrogen laser-pumped pulsed dye lasers in the inductively-coupled plasma (ICP) are studied. Noise sources are investigated and detection limits are compared to the techniques of ICP-emission and laser-excited atomic fluorescence spectrometry.     

Atomic absorption spectrometry of vanadium with a tungsten electrothermal atomizer

A detailed study of the atomic absorption characteristics of vanadium with a tungsten micro-tube atomizer is presented. The absolute sensitivities (1% absorption) were 2 × lO^-10 and 4 × 10^-11 g of vanadium for ammonium vanadate and the vanadium N-benzoyl-N-phenylhydroxylamine complex, respectively. Diverse elements and acids have pronounced depressive effects, but vanadium may be determined in rocks after selective extraction of the above complex into chloroform.     

Atomic absorption spectrometry of germanium with a tungsten electrothermal atomizer

The electrothermal atomization of germanium in a metal micro-tube atomizer is described. Tungsten is preferable to other metals for the atomizer. Hydrogen lowers the atomization temperature of germanium, and improves the sensitivity for germanium significantly when the optimum flow rates are applied. There are pronounced interferences from diverse elements and acids on the atomization of germanium. A procedure which involves carbon tetrachloride extraction of germanium tetrachloride and back-extraction of germanium into water avoids many of the interferences and is recommended for rock samples.     

Determination of thallium by electrothermal atomic absorption spectrometry with a metal atomizer

Summary Electrothermal atomization of thallium in a molybdenum microtube atomizer is described. The addition of a low flow rate of hydrogen to argon purge gas resulted in higher peak absorption. In the presence of thiourea the addition of hydrogen did not alter the peak absorption value in pure argon, although the peak temperature shifted to lower region. A high heating rate of the atomizer was recommended for higher peak absorption and improvement of interferences from concomitants. The interferences by concomitants at 50 ng level were modified with thiourea. Modification with thiourea was effective even for interferences from 500 ng of cadmium, zinc or copper, while it was insufficient for 500 ng of calcium, magnesium, chromium, bismuth or lead. Provided the atomization of thallium was carried out at high heating rate and on addition of thiourea as a matrix modifier, the interference from chloride (500 ng) was modified. The absolute sensitivity (0.0044 abs) for thallium was 1.2 pg.

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Thalliumbestitmmung durch AAS mit elektrothermischer Atomisierung in einem metallischen Atomizer

Zusammenfassung Zur AAS-Bestimmung von Thallium wird eine Molybdän-Mikroröhre als Atomizer empfohlen. Zusatz von geringeren Wasserstoffmengen zum Argongas ergab eine höhere Absorption. In Gegenwart von Thioharnstoff erfolgte durch Wasserstoff-Zugabe keine Änderung des Absorptionswertes in reinem Argon, obwohl die Peaktemperatur in einen niederen Bereich verschoben wurde. Für höhere Absorption und zur Verminderung von Störungen durch Begleitelemente wurden höhere Erhitzungsgeschwindigkeiten empfohlen. Störungen durch Begleitelemente im Bereich von 50 ng konnten mit Thioharnstoff verringert werden. Die Zugabe von Thioharnstoff erwies sich ebenfalls als wirksam für 500 ng Cadmium, Zink oder Kupfer, während sie für dieselben Mengen an Calcium, Magnesium, Chrom, Bismut oder Blei ungenügend war. Mit hoher Erhitzungsgeschwindigkeit und Thioharnstoffzusatz konnte eine Störung durch Chlorid im Bereich von 500 ng reduziert werden. Die absolute Empfindlichkeit für Thallium (0,0044 abs) betrug 1,2 pg.

     

Laser-Induced fluorescence detection in conventional-size liquid chromatography with a frequency-doubled argon-ion laser

Laser-induced fluorescence (LIF) detection in conventional-size column liquid chromatography is achieved at 257 nm with a frequency-doubled argon-ion laser. Short-wavelength excitation offers two important advantages: firstly, a wide variety of analytes can be excited, and secondly, the Raman scatter of the eluent does not interfere with the fluorescence of the analytes. A standard mixture of polynuclear aromatic hydrocarbons was studied, both with LIF detection and with a commercially available sensitive conventional fluorescence detector. The improvement in the detection limits ranges from about a factory of 4 to 30; the LIF detection limits are typically at the 50 ng l^?1 level, which corresponds to an injected amount of 0.5 pg.     

Sub-picogram detection of lead by non-flame atomic fluorescence spectrometry with dye laser excitation

The frequency-doubled radiation of flashlamp-pumped dye laser has been compared with the radiation of an eleotrodeless discharge lamp (EDL) and a hollow cathode lamp (HCL) as excitation light sources in non-flame atomic fluorescence spectrometric (AFS) measurements. Detection limits and linear ranges of the analytical working curves have been studied. The aqueous Pb sample solutions used in this study were atomized in an electrically heated graphite rod. Direct line fluorescence at 405.8 nm has been observed. The limit of detection obtained with the laser as excitation source is about one order of magnitude lower than the detection limits obtained with the EDL and HCL. The absolute limit of detection of 0.2 pg is the lowest reported value to date attained in any atomic spectrometric method. The ultraviolet laser irradiance was found to be high enough to approach saturation conditions. As a result selfabsorption of the exciting laser beam is reduced and the linear range of the analytical working curve is extended to higher analyte concentrations.     

原子吸收和原子荧光光谱分析

本文是《分析试验室》期刊定期评述中关于原子吸收光谱(AAS)及原子荧光光谱(AFS)分析的第11篇综述文章. 文中对2004年12月～2007年4月期间我国在AAS/AFS领域所取得的主要进展进行评述. 内容包括概述、仪器装置与数据处理、火焰原子吸收光谱法、电热原子吸收光谱法、化学蒸气发生技术以及原子荧光光谱法等. 收集文献670篇.     

Intracavity laser atomic absorption spectrometry with graphite furnace atomizer or pulsed laser sampler

An absorption intracavity laser spectrometer with two types of sample vaporization systems (graphite furnace electrothermal atomizer or laser sampler) is described that can be used for the determination of trace amounts of metals (Al, Cr, Fe and Mn) in liquid samples and at the surface of solid targets. The limits of detection for the elements tested are lower than those obtained by modern conventional spectrometers. The examined technique provides a wide dynamic range of linear standard calibration curves.     

Intracavity laser atomic absorption spectrometry with graphite furnace atomizer or pulsed laser sampler

An absorption intracavity laser spectrometer with two types of sample vaporization systems (graphite furnace electrothermal atomizer or laser sampler) is described that can be used for the determination of trace amounts of metals (Al, Cr, Fe and Mn) in liquid samples and at the surface of solid targets. The limits of detection for the elements tested are lower than those obtained by modern conventional spectrometers. The examined technique provides a wide dynamic range of linear standard calibration curves.     

Indirect laser-induced fluorescence detection for capillary electrophoresis using a frequency-doubled diode laser

A blue (452 nm) frequency-doubled diode laser with a quasi-cw optical output power of 10 microW is used for indirect laser-induced fluorescence detection in combination with the capillary electrophoretic separation of inorganic anions. As fluorescing probe ion the anion of 8-hydroxypyrene-1,3,6-trisulfonic acid (HPTS) was selected having an absorption maximum of 454 nm in alkaline medium. Employing a capillary coated with linear acrylamide, baseline separation of eight inorganic anions was possible within 5 min. With a separation buffer containing 50 micromol.L(-1) HPTS and 10 mmol.L(-1) lysine the limits of detection for sulfate, nitrite, nitrate, azide, thiocyanate, and chlorate were between 0.9 and 4.7 micromol.L(-1). Separation of chloride and sulfate was achieved by adding 0.25 mmol.L(-1) calcium hydroxide to the separation buffer. Inorganic anions in several mineral and tap water samples have been determined with the technique developed and results are compared to data obtained by ion chromatography in combination with conductivity detection after conductivity suppression.     

Spectroscopy of the E band of SO2 with a frequency-doubled single-mode dye laser

The rotational structure of the E band of SO₂ between 32720 and 32900 cm^?1 has been investigated by absorption spectroscopy with reduced Doppler width in a cooled cell at 190 K using a frequency-doubled cw single-mode dye laser. More than 400 lines in this band could be assigned, starting from a former partial analysis by Hamada and Merer. Severe perturbations in the upper state impede the assignment and prevent the unambiguous identification of many other lines in the spectrum. From the measured lines term values and molecular constants of the upper levels are derived. A comparison with spectra of very high resolution, taken in a collimated supersonic SO₂ beam demonstrates that the actual line density is by far higher than the spectral resolution in the cooled cell.     

Atomic fluorescence flame spectrometry using a mercury line source

The possibility of exciting the fluorescence of several elements with the “overlapping” lines of other elements and the effectiveness of exciting the fluorescence of Fe, Mn, Ni, Cr, Tl, Cu and Mg with a 90 W mercury discharge lamp, are discussed. A method of increasing the fluorescence radiation by suitable optics, with a simple adaptation of a Jarrell-Ash AA spectrometer, is described. A two-pass system of the incident radiation into the flame is coupled with a mirror, in the optical axis, which reflects the fluorescence radiation emitted at the opposite side to the monochromator slit. This produces an increase of 168% of the signal. Detection limits for 10 elements are reported.     

Atomic absorption spectrometric studies of the atomization of boron from a carbon rod atomizer

Boron (<20 μg ml^?1) in aqueous solutions gives no absorbance but addition of ascorbic acid, especially with titanium greatly enhances the signal, leading to a detection limit of 0.2 μg ml^?1 boron. The presence of uranium (<10 mg ml^?) only slightly decreases the boron signal.     

Electrothermal atomic-absorption and atomic-fluorescence spectrometry with a tungsten-coil atomizer

A pulsed electrothermal atomizer of the tungsten-coil type and apparatus for its application in atomic-absorption and atomic-fluorescence spectrometry are described. A tungsten-coil atomizer is shown to be just as good as commercial electrothermal atomizers with regard to sensitivity and reproducibility, but to have better operating characteristics. A theoretical model for formation of the atom cloud is given. Mechanisms for atomization of different groups of element in an atmosphere of pure argon and in the presence of reductants (hydrogen and carbon) are proposed.     

Non-dispersive atomic fluorescence spectrometry with a carbon filament atom reservoir

The non-dispersive atomic fluorescence spectrometric determination of Bi, Cd, Hg, Te, Tl and Zn on a carbon filament atom reservoir with electrodeless discharge lamp sources and reflecting microscope objective lenses is described. The non-dispersive system shows distinct advantages for an element such as tellurium whose principal fluorescence lines fall within the useful range of the solar-blind photomultiplier detector, and marginal advantages for mercury, cadmium and zinc where only one line is within the detector range. It is inferior for bismuth, thallium and lead where lines lie at the extremes of the useful detector range. The technique was applied successfully to the determination of cadmium (0.012%) in a copper-base alloy.     

Determination of lead in petroleum and petroleum products by atomic absorption spectrometry with a carbon rod atomizer

The use of a carbon rod atomizer for the analysis of lead in petroleum and petroleum products is described. Variables affecting sensitivity studied include: type of lead salt and type of solvent for standard and sample preparation, hydrogen diffusion flame, choice of analytical wavelength and interferences. For the 217.00-nm line, a sensitivity of 1·10^-11 g (absolute) and for the 283.31-nm line, a detection limit of 2·10^-12 g (absolute) are reported. Results of analysis of gasoline, used bunker heating oil, used jet engine lubricating oil, and crude oil for lead content are presented. An organic-to-aqueous solvent extraction system for lead is described.     

Determination of manganese in natural waters by atomic absorption spectrometry with a carbon tube atomizer.

A method is described for the accurate and precise determination of alumina and silica in bauxites with the aid of a ²²⁷Ac-Be isotopic neutron source with a total neutron output of 10⁸ n s^-1. Three ores can be analysed in triplicate within 4 h, including the determination of the natural radioactivity of the ores. Samples are pellets pressed from a mixture of 4.5 g of powdered bauxite and 0.9 g of a wax as pelleting agent. The special flux distributions of the source allow irradiations at very different fast-to-thermal flux ratios without cadmium neutron absorbers. The drying and water re-uptake of bauxite and the natural radioactivity in these ores are discussed. The method was tested with several certified standards. A relative precision of 0.7% for the alumina determination was obtained for triplicate analyses. Vanadium is the only interfering element, the concentration of which should be determined separately or estimated; a correction procedure is given.     

Atomic absorption and fluorescence spectrometry with a carbon filament atom reservoir: Part XIII The determination of chromium with a fully enclosed atom reservoir

The detection and measurement of chromium by atomic absorption spectrometry with a carbon filament atom reservoir is described. At a wavelength of 357.9 nm, a sensitivity (1% absorption) of 9.2·10^-12 g was obtained. The detection limit was 1·1O^-11 g; in terms of concentration this is similar to that normally detectable in a flame. Results are presented for the effects of a number of interfering species.     

Atomic fluorescence spectrometry of mercury: principles and developments

Atomic fluorescence spectrometry (AFS) of mercury is very sensitive and the AFS system is an excellent detector for mercury analysis. The first part of this review covers the principles of determination of mercury by AFS. The second part delineates the loss and increase of mercury through its transfer between the gas and solution phases. The third part addresses some possible interferences in the determination of mercury by AFS. The fourth part describes preconcentration techniques for mercury species. In the fifth part, methods for total and selective determination of mercury are described. In the sixth part, various types of automated and semi-automated procedures for the determination of mercury are summarized. Finally, representative biological and environmental certified reference materials (CRMs) for mercury analysis are presented and the availability of CRMs in checking the accuracy and precision of the methodologies is briefly described.