Axially viewed ICP

The signal-to-noise ratio on an axially viewed ICP was studied for different lines of the elements and the best conditions were sought... 

M. Grotti, C. Lagomarsino and J. M. Mermet, Effect of operating conditions on excitation temperature and electron number density in axially-viewed ICP-OES with introduction of vapors or aerosols, J. Anal. At. Spectrom., 21(9), 2006, 963-969. 

Bridger S, Knowles M (2000) ICP-AES at work - ICP-29. A complete method for environmental samples by simultaneous axially viewed ICP-AES following USEPA guidelines. Varian Australia Pty Ltd. 

Yttrium was found to be effective for signal compensation in the detection of boron and titanium in human blood using axial-view ICP optical emission spectrometry (Garavaglia et al. 2002). 

The plasma characteristics of an axially viewed ICP where amounts of vapours or aerosols were injected were investigated. Experimental designs and empirical modelling (multivariate linear regression) were combined to select robust conditions. 

The best conditions to operate an axially viewed ICP were set employing experimental designs. The multivariate effect of carrier gas flow and RF power on several analytical figures of merit was studied. Multivariate regression and principal component analysis were used as well to model the system. 

The principle is exactly the same as radial ICP-OES, except that in axial-view ICP-OES, the plasma is viewed horizontally (end-on). The benefit is that more photons are seen by the detector and as a result, detection limits can be as much as 2-10 times lower, depending on the design of the instrument. The disadvantage is that more severe matrix interferences are observed with an axial ICP. Sample requirements are the same as for radial ICP-OES. 

Brenner I. B., Zischka M., Maichin B. and Knapp G. (1998) Ca and Na interference effects in an axially viewed ICP using low and high aerosol loadings, f. Anal. At. Spectrom. 

Brenner 1. B., Vats S. and Zander A. T. (1999) A new CCD axially viewed ICP atomic emission spectrometer for simultaneous multi-element geoanalysis. Determination of major and minor elements in silicate rocks,... 

Typical configuration for ICP-AES instruments (a) side -on viewing of the ICP (b) axial viewing... 

Radial or axial view of spontaneous emission occurring in ICP... 

Figure 2.8 Comparative peak height for 1.0 pg ml 1 (ppm) B using radial and axial viewing. Scans obtained using Perkin Elmer dual view Optima 2100DV ICP-OES...

Detection of extremely low levels of metals may be possible by the use of hyphenated techniques such as hydride generation, ICP-OES/graphite furnace, ultrasonic nebuliser and cold vapour trap for Hg, and by utilising the axial viewing mode of the ICP-OES could achieve results close to ICPMS levels. Table 7.14 shows a brief list of metals and methods that are commonly considered for food analysis. 

FIGURE 10-1 A typical ICP source. Position A shows radial viewing of the torch, and position B shows axial viewing. (From V. A. Fassel. Science. 1978.202,185. With permission. Copyright 1978 by the American Association for the Advancement of Science.)... 

Sequential and simultaneous ICP systems of many types are available from numerous instrument manufacturers. Most are available in radial or axial view, or both. Most spectrometers can be purged to reach 160 nm. Examples of some of the companies who make ICPs and DCPs are given. Jobin Yvon, Inc. makes a line of PMT-based high-resolution sequential systems, simultaneous systems, and combination sequential-simultaneous systems. PerkinElmer Inc. makes a scanning ICP with CCD detection, and a line of simultaneous CCD-based Echelle systems. Leeman Laboratories, Inc. makes an Echelle ICP spectrometer with an aperture grid available as a sequential system with rapid scanning PMT detection, a simultaneous system with a PMT array, and a combination system. Varian, Inc. makes a sequential ICP with PMT detection and a simultaneous system with CCD detection. ThermoElemental offers ICP Echelle spectrometers with CID detection and a sequential diffraction grating instmment with PMT detection. 

In the analysis of simple solutions with known composition, for ICP-AES short term precision between 0.2 3 % relative standard deviation for analytes with concentrations ten times the detection Hmits may be achieved, while over several hours a 5 % RSD can be expected. This precision in combination with its robustness make ICP-AES superior to ICP-MS for the determination of minor and major components. With ICP-AES most elements (about 73) can be determined routinely at the 10 pg L level or better in solution with radial viewing. In favourable cases and/or axial viewing, detection Hmits < 1 pg can be achieved. Eor a single emission line, a Hnear range of four orders of magnitude may be easily attained and as many as six orders of magnitude can be observed in favourable cases. 

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