Inductively couple plasma sources

Spectroscopic methods for the deterrnination of impurities in niobium include the older arc and spark emission procedures (53) along with newer inductively coupled plasma source optical emission methods (54). Some work has been done using inductively coupled mass spectroscopy to determine impurities in niobium (55,56). X-ray fluorescence analysis, a widely used method for niobium analysis, is used for routine work by niobium concentrates producers (57,58). Paying careful attention to matrix effects, precision and accuracy of x-ray fluorescence analyses are at least equal to those of the gravimetric and ion-exchange methods. 

The inductively coupled plasma source (Fig. 20.11) comprises three concentric silica quartz tubes, each of which is open at the top. The argon stream that carries the sample, in the form of an aerosol, passes through the central tube. The excitation is provided by two or three turns of a metal induction tube through which flows a radio-frequency current (frequency 27 MHz). The second gas flow of argon of rate between 10 and 15 L min-1 maintains the plasma. It is this gas stream that is excited by the radio-frequency power. The plasma gas flows in a helical pattern which provides stability and helps to isolate thermally the outside quartz tube. 

Gray AL (1985). Solid sample introduction by laser ablation for inductively coupled plasma source mass spectrometry. Analyst 110 551-556... 

Delves HT, Campbell MJ. 1988. Measurements of total lead concentrations and of lead isotope ratios in whole blood by use of inductively coupled plasma source mass spectrometry. J Analytical Atomic Spectrometry 3 343-348. 

Generally, extensive prior information is known about the sample in terms of the elemental composition and in these cases methods of analysis can be selected that will provide the desired result. However, if this information is not available or else a more general survey of ultratrace elements is required, then AES with an inductively coupled plasma source is the only atomic spectrometric technique that can provide these data at ultratrace levels. 

Figure 5. The inductively-coupled plasma source (inspired by Niu and Houk 1996). The original figure has been modified to show the electrical potentials, the vacuum cascade (top), and the distribution of ions and neutral (bottom) in an MC-ICP-MS similar to the VG Plasma 54. The zone with incipient voltage acceleration right behind the skimmer show maximum space-charge effect with the lighter ions being most efficiently driven off by the strong axial current of positive ions.

Date AR, Ying Y, Stuart ME (1987) The influence of polyatomic ion interferences in analysis by inductively coupled plasma source mass spectrometry (ICP-MS). Spectrochim Acta 42B 3-20... 

Bensimon M, Bourquin J, Parriaux A (2000) Determination of ultra-trace elements in snow samples by inductively-coupled plasma source sector field mass spectrometry using ultrasonic nebulization. J Anal Atom Spectrom 15 731-734... 

With the advent of multiple-collector inductively coupled plasma-source mass spectrometry (MC-ICPMS) it is now possible to measure Mg/ Mg and Mg/ Mg of Mg in solution with a reproducibility of 30 to 60 ppm or better (Galy et al. 2001). What is more, ultraviolet (UV) laser ablation combined with MC-ICPMS permits in situ analysis of Mg-bearing mineral samples with reproducibility of 100 to 200 ppm (Yoimg et al. 2002a). These new analytical capabilities allow mass-dependent fractionations of the isotopes of Mg to be used as tracers in natural systems. 

The observed range of natural variations of 5 Ca is about 4 to 5%o in terrestrial materials and up to 50%o in high temperature condensate minerals in carbonaceous chondrites. The typical reproducibility of measurements is about +0.15%o. Broader application of Ca isotope measurements in geochemistry may be possible, particularly if the reproducibility can be improved to 0.05%o to 0.03%o. There is hope that this can be achieved either with inductively coupled plasma source mass spectrometry (Halicz et al. 1999) or with a new generation of multi-collector thermal ionization mass spectrometers (Heuser et al. 2002). 

Fortescue,). A. C., Silvester, M. D., Abercrombie, F. N., The Chemical Composition of Sludge from Six Sewage Plants in the Niagra Penninsula, Ontario, Canada as Determined by Atomic Absorption and Emission Spectroscopy Using an Inductively Coupled Plasma Source , Proceedings of the 9th Annual Conference on Trace Substances in Environmental Health, Columbia, Missouri, June, (1975). 

Montaser, A. (ed.), Inductively Coupled Plasma Source Mass Spectrometry, Wiley-VCH Inc., New York (1998). 

Various efficient devices have been utilized for sample introduction into an inductive plasma source, for example the application of several nebulizers, hyphenated techniques, hydride generation, laser ablation and electrothermal vaporization. The role of the solution introduction system in an inductively coupled plasma source is to convert the liquid sample into a suitable form (e.g.,... 

Figure 2.12 Overview of different sample introduction systems in an inductively coupled plasma source. (]. S. Becker and H. ]. Dietze, Spectrochim. Acta 53B, 1475 (1998). Reproduced by permission of Elsevier.)...

Hydride Generation and Cold Vapour Technique Coupled to an Inductively Coupled Plasma Source... 

As an alternative to commercial quadrupole based ICP-MS measurements at low mass resolution ( / 300), in 1996 Yiang and Douglas15 proposed a quadrupole ICP-MS system which allows a maximum mass resolution of 9000. At a mass resolution of 5000 the sensitivity was comparable to that of a commercial double-focusing sector field ICP-MS operated at the same mass resolution. Due to the very high continuum instrumental background of about lOOOcps no commercial high resolution quadrupole instrumentation with an inductively coupled plasma source exists and the development of high resolution quadrupole based ICP-MS has ceased. 

An easy calibration strategy is possible in ICP-MS (in analogy to optical emission spectroscopy with an inductively coupled plasma source, ICP-OES) because aqueous standard solutions with well known analyte concentrations can be measured in a short time with good precision. Normally, internal standardization is applied in this calibration procedure, where an internal standard element of the same concentration is added to the standard solutions, the samples and the blank solution. The analytical procedure can then be optimized using the internal standard element. The internal standard element is commonly applied in ICP-MS and LA-ICP-MS to account for plasma instabilities, changes in sample transport, short and long term drifts of separation fields of the mass analyzer and other aspects which would lead to errors during mass spectrometric measurements. 

Because ICP-MS with different instrumentations and sample introduction systems (besides solution nebulization, also laser ablation or hyphenated methods, such as HPLC, CE, SPME) is today the most frequently used analytical technique for precise and accurate isotope ratio measurements, the following section will mainly focus on this form of mass spectrometry with an inductively coupled plasma source. 

Different analytical techniques such as ICP-OES (optical emission spectrometry with inductively coupled plasma source), XRF (X-ray fluorescence analysis), AAS (atomic absorption spectrometry) with graphite furnace and flame GF-AAS and FAAS, NAA (neutron activation analysis) and others, are employed for the trace analysis of environmental samples. The main features of selected atomic spectrometric techniques (ICP-MS, ICP-OES and AAS) are summarized in Table 9.20.1 The detection ranges and LODs of selected analytical techniques for trace analysis on environmental samples are summarized in Figure 9.15.1... 

Part V Inductively Coupled Plasma Sources for use in Emission... 

Hund M, Herold H (2007) Design of a scanning probe microscope with advanced sample treatment capabilities an atomic force microscope combined with a miniaturized inductively coupled plasma source. Rev Sci Instrum 78(6) 063703... 

The typical ICP-MS instrument (Fig. 3.1) consists of a sample introduction system (a nebulizer and spray chamber), an inductively coupled plasma source, a differ-... 

Russ, G.R III, and Bazan, J.M. (1987) Isotopic ratio measurements with an inductively coupled plasma source mass spectrometer. Spectrochim. Acta 42B, 49-62. 

An inductively coupled plasma source is made up of a hot flame produced by inductive coupling in which a solution of the sample is introduced as a spray [102-104], This source consists of three concentric quartz tubes through which streams of argon flow. As shown in Figure 1.44, a cooled induction coil surrounds the top of the largest tube. This coil is powered by an RF generator that produces between 1.5 and 2.5 kW at 27 or 40 MHz typically. The gas at atmospheric pressure that sustains the plasma is initially made... 

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