Laser atomic spectrometry

Glow discharges have also now been miniaturized. In the discharge in a micro-structured system, described by Eijkel et al. [607], molecular emission is obtained and the system can be used successfully to detect down to 10 14 g/s methane with a linear response over two decades. A barrier-layer discharge for use in diode laser atomic spectrometry has also been described recently (Fig. 122) [608],... 

Toschek and coworkers 345) used a technique called tuned laser differential spectrometry which is based on simultaneous interaction of gas atoms with two different laser beams, one of these being a weak probe beam the tuning of which scans the saturation on the common level of the two transitions induced by the other beam 346) The experiment employed the two He-Ne laser lines at X = 1.15 ju and X = 0.6328 which share the common lower level. 

Wilson, S.A., Ridley, W.I., Koenig, A.E. 2002. Development of sulfide calibration standards for the laser ablation inductively-ooupled plasma mass spectrometry technique. Journal of Analytical Atomic Spectrometry 17, 406-409. 

Fabre, C., Boiron, M.-C., Dubessy, J., Moissette, a. 1999. Determination of ions in individual fluid inclusions by laser ablation optical emission spectroscopy development and applications to natural fluid inclusions. Journal of Analytical Atomic Spectrometry, 14(6), 913-922. 

CONTENTS Preface, Joseph Sneddon. Analyte Excitation Mechanisms in the Inductively Coupled Plasma, Kuang-Pang Li and J.D. Winefordner. Laser-Induced Ionization Spectrometry, Robert B. Green and Michael D. Seltzer. Sample Introduction in Atomic Spectroscopy, Joseph Sneddon. Background Correction Techniques in Atomic Absorption Spectrometry, G. Delude. Flow Injection Techniques for Atomic Spectrometry, Julian F. Tyson. 

Ballihaut, G., Tastet, L., Pecheyran, C., Bouyssiere, B., Donard, O., Grimaud, R., and Lobinski, R., Biosynthesis, purification and analysis of selenomethionyl calmodulin by gel electrophoresis-laser ablation-ICP-MS and capillary HPLC-ICP-MS peptide mapping following in-gel tryptic digestion. Journal of Analytical Atomic Spectrometry 20(6), 493 99, 2005. 

M. A. Bolshov, C. F. Boutron, F. M. Ducroz, U. Gorlach, O. M. Kompanetz, S. M. Rudniev, B, Hutch, Direct ultratrace determination of cadmium in Antarctic and Greenland snow and ice by laser atomic fluorescence spectrometry. Anal. Chim. Acta, 251 (1991), 169-175. 

M. A. Bolshov, S. N. Rudniev, J. P. Candelone, C. F. Boutron, S. Hong, Ultratrace determination of Bi in Greenland snow by laser atomic fluorescence spectrometry, Spectrochim. Acta, 49B (1994), 1445-1452. 

Williams, J.G. Jarvis, K.E. (1993) Preliminary assessment of laser ablation inductively coupled plasma mass spectrometry for quantitative multielement determination of silicates. Journal of Analytical and Atomic Spectrometry 8, 25-34. 

Laser-excited atomic fluorescence spectrometry is capable of extremely low detection limits, particularly when combined with electrothermal atomization. Detection limits in the femtogram (10 g) to attogram (10 g) range have been shown for many elements. Commercial instrumentation has not been developed for laser-based AFS, probably because of its expense and the nonroutine nature of high-powered lasers. Atomic fluorescence has the disadvantage of being a singleelement method unless tunable lasers with their inherent complexities are used. 

Sources for atomic spectrometry include flames, arcs, sparks, low-pressure discharges, lasers as well as dc, high-frequency and microwave plasma discharges at reduced and atmospheric pressure (Fig. 5) [28], They can be characterized as listed in Table 2. Flames are in thermal equilibrium. Their temperatures, however, at the highest are 2800 K. As this is far below the norm temperature of most elemental lines, flames only have limited importance for atomic emission spectrometry, but they are excellent atom reservoirs for atomic absorption and atomic fluorescence spectrometry as well as for laser enhanced ionization work. Arcs and sparks are... 

In a system for coherent forward scattering, the radiation of a primary source is led through the atom reservoir (a flame or a furnace), across which a magnetic field is applied. When the atom reservoir is placed between crossed polarizers scattered signals for the atomic species occur on a zero-background. When a line source such as a hollow cathode lamp or a laser is used, determinations of the respective elements can be performed. In the case of a continuous source, such as a xenon lamp, and a multichannel spectrometer simultaneous multielement determinations can also be performed. The method is known as coherent forward scattering atomic spectrometry [309, 310]. This approach has become particularly interesting since flexible multichannel diode array spectrometers have became available. 

Coherent forward scattering (CFS) atomic spectrometry is a multielement method. The instrumentation required is simple and consists of the same components as a Zeeman AAS system. As the spectra contain only some resonance lines, a spectrometer with just a low spectral resolution is required. The detection limits depend considerably on the primary source and on the atom reservoir used. When using a xenon lamp as the primary source, multielement determinations can be performed but the power of detection will be low as the spectral radiances are low as compared with those of a hollow cathode lamp. By using high-intensity laser sources the intensities of the signals and accordingly the power of detection can be considerably improved. Indeed, both Ip(k) and Iy(k) are proportional to Io(k). When furnaces are used as the atomizers typical detection limits in the case of a xenon arc are Cd 4, Pb 0.9, T11.5, Fe 2.5 and Zn 50 ng [309]. They are considerably higher than in furnace AAS. 

In addition, for speciation coupling of flow injection analysis and column chromatography with flame AAS and also a direct coupling of HPLC with flame AAS, as is possible with high-pressure nebulization, are most powerful. Here the Cr line in the visible region can be used, which makes the application of diode laser atomic absorption spectrometry possible [325]. This has been shown recently by the example of the determination of methylcyclopentadienyl manganese tricarbonyl. 

Tab. 18. Detection limits in laser atomic fluorescence spectrometry.

Niemax K., Zybin A., Schnurer-Patschan C. and Groll H. (1996) Semiconductor diode lasers in atomic spectrometry, Anal Chem 68 351A-356A. 

Groll H., Schnurer-Patschan C., Kuritsyn Yu. and Niemax K. (1994) Wavelength modulation diode laser atomic absorption spectrometry in analytical flames, Spectrochim Acta, Part B 49 1463-1472. 

Speciation of methylcyclopentadienyl manganese tricarbonyl by high performance liquid chromatography-diode laser atomic absorption spectrometry, Anal Chem 71 5379-5385. 

Not only is there a need for the characterization of raw bulk materials but also the requirement for process controled industrial production introduced new demands. This was particularly the case in the metals industry, where production of steel became dependent on the speed with which the composition of the molten steel during converter processes could be controlled. After World War 11 this task was efficiently dealt with by atomic spectrometry, where the development and knowledge gained about suitable electrical discharges for this task fostered the growth of atomic spectrometry. Indeed, arcs and sparks were soon shown to be of use for analyte ablation and excitation of solid materials. The arc thus became a standard tool for the semi-quantitative analysis of powdered samples whereas spark emission spectrometry became a decisive technique for the direct analysis of metal samples. Other reduced pressure discharges, as known from atomic physics, had been shown to be powerful radiation sources and the same developments could be observed as reliable laser sources become available. Both were found to offer special advantages particularly for materials characterization. 

O. 2008. Physical and chemical characteristics of particles produced by laser ablation of biogenic calcium carbonate. Journal of Analytical Atomic Spectrometry, 23, 240-243. 

Kuhn, H. R. Gunther, D. 2004. Laser ablation ICP-MS Particle size dependent elemental composition studies on filter-collected and online measured aerosols from glass. Journal of Analytical Atomic Spectrometry, 19, 1158-1164. 

Bolshov MA, Boutron CF, Zybin ZV (1989) Determination of lead in Antarctic ice at picogram-per-gram level by laser atomic fluorescence spectrometry. Anal Chem 61 1758-1762... 

---