Spectroscopy with inductively coupled plasmas analysi

The most frequently applied analytical methods used for characterizing bulk and layered systems (wafers and layers for microelectronics see the example in the schematic on the right-hand side) are summarized in Figure 9.4. Besides mass spectrometric techniques there are a multitude of alternative powerful analytical techniques for characterizing such multi-layered systems. The analytical methods used for determining trace and ultratrace elements in, for example, high purity materials for microelectronic applications include AAS (atomic absorption spectrometry), XRF (X-ray fluorescence analysis), ICP-OES (optical emission spectroscopy with inductively coupled plasma), NAA (neutron activation analysis) and others. For the characterization of layered systems or for the determination of surface contamination, XPS (X-ray photon electron spectroscopy), SEM-EDX (secondary electron microscopy combined with energy disperse X-ray analysis) and... 

This presentation will summarize developments in laser ablation with emphasis on LIBS (laser induced breakdown spectroscopy) and inductively coupled plasma mass spectrometry (ICPMS) as analytical tools for real time chemical analysis (Fig. 1) (Russo et al. 

Since the mid-1960s, a variety of analytical chemistry techniques have been used to characterize obsidian sources and artifacts for provenance research (4, 32-36). The most common of these methods include optical emission spectroscopy (OES), atomic absorption spectroscopy (AAS), particle-induced X-ray emission spectroscopy (PIXE), inductively coupled plasma-mass spectrometry (ICP-MS), laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray fluorescence spectroscopy (XRF), and neutron activation analysis (NAA). When selecting a method of analysis for obsidian, one must consider accuracy, precision, cost, promptness of results, existence of comparative data, and availability. Most of the above-mentioned techniques are capable of determining a number of elements, but some of the methods are more labor-intensive, more destructive, and less precise than others. The two methods with the longest and most successful histoty of success for obsidian provenance research are XRF and NAA. 

Atomic absorption spectroscopy is commonly used to determine Fe, Al, Mn, Cr and other metals. Standard solutions should be prepared with the same acid concentration as that of the test solutions. Apart from Al which requires a nitrous oxide/acetylene flame, these cations may be measured using an air/acetylene flame. These metals may also be measured by inductive coupled plasma analysis (ICP). 

Recent developments in ion chromatography are filling the analytical gap between the atomic adsorption spectroscopy and inductively coupled plasma metal spectroscopy. Ion chromatography can now not only determine what trace metals are present, but also their oxidation state, the degree of complexation, and the stability of the complex. For example, a nickel electroplating solution was analyzed by diluting it with a water eluant solution. The analysis revealed the following ion concentrations. 

In the past, the most common method of analysis of small anions has been ion-exchange chromatography. For cations, the preferred techniques have been atomic absorption spectroscopy and inductively coupled plasma emission spectroscopy. Recently, however, capillary electrophoretic methods have begun to compete with these traditional methods for small ion analysis. Several major reasons for adoption of electrophoretic methods have been recognized lower equipment costs, smaller sample size requirements, much greater speed, and better resolution. 

Important to quality control are the comparison and confirmation of drug substance identity, excipients, and packaging components. Techniques such as Fourier transform IR (FTIR), attenuated total reflectance (ATR), NIR, Raman spectroscopy are used with increased regularity. The detection of foreign metal contaminants is essential with inductively coupled plasma spectroscopy (ICP), atomic absorption (AA), and X-ray fluorescence. Also notable is the increased attention to analysis of chiral compounds, as in the synthesis of drug substances. Optical rotation, ORD, and CD are currently the preferred instruments for this practice. The analytical techniques commonly used in the preformulation study are discussed in the following. 

Among the various types of atomic spectroscopy, only two, flame emission spectroscopy and atomic absorption spectroscopy, are widely used and accepted for quantitative pharmaceutical analysis. By far the majority of literature regarding pharmaceutical atomic spectroscopy is concerned with these two methods. However, the older method of arc emission spectroscopy is still a valuable tool for the qualitative detection of trace-metal impurities. The two most recently developed methods, furnace atomic absorption spectroscopy and inductively coupled plasma (ICP) emission spectroscopy, promise to become prominent in pharmaceutical analysis. The former is the most sensitive technique available to the analyst, while the latter offers simultaneous, multielemental analysis with the high sensitivity and precision of flame atomic absorption. 

The final step in the synthesis of 9 is the saponification of the ester in 16, followed by precipitation by acidification, and filtration (Scheme 4.3). Although HCl was used for this purpose when 9 was made in-house, the vendor utilized acetic acid. The by-product of this transformation is potassium acetate and could be a potential contaminant in 9. Further support for this hypothesis was garnered by analysis of the filtrate obtained after washing the implicated batch of 9 with water and methanol, which revealed the presence of potassium (by qualitative elemental x-ray microanalysis) and acetate (by Fourier transform infrared [FT-IR] spectroscopy). ICP (inductively coupled plasma) tests did not show the presence of any other ionic impurities at significant levels. 

Each experiment was accortqjanied the determination of Pd in solution after hot filtration of the solid catalyst at the end of the reaction. Because simple Atomic Absorption Spectroscopy (AAS) was found to not be precise enough for the palladium analysis in this concentration range (detection limit too high.) ICP-OES and/or ICP-MS (Inductively Coupled Plasma - Optical Emission Spectroscopy or Inductively Coupled Plasma - Mass Spectrometry) were applied. To first approximation, the Pd leaching could not be correlated with the properties of the twelve different Pd/C catalysts described above ((1) Correlation of catalyst structure and activity.) There is, however, a strong correlation with the reaction parameters as described below. 

P. W. Alexander, R. J. Finlayson, L. E. Smythe, and A. Thalib, Rapid Flow Analysis with Inductively Coupled Plasma Atomic-Emission Spectroscopy Using a Micro-Injection Technique. Analyst, 107 (1982) 1335. 

K. E. LaFreniere, G. W. Rice, and V. A. Fassel, Flow Injection Analysis with Inductively Coupled Plasma-Atomic Emission Spectroscopy Critical Comparison of Conventional Pneumatic, Ultrasonic and Direct Injection Nebulization. Spectrochim. Acta Pt. B—At. Spec., 40 (1985) 1495. 

Laakso et al. (2001) developed a method for boron determination that uses inductively coupled plasma atomic emission spectrometry and protein removal with trichloroacetic acid before analysis. This method is feasible, accurate, and one of the fastest for boron determination during BNCT and enables a more reliable estimation of the irradiation dose. Yoshida et al. (2002) used flow cytometry to sort the cells by phases, and the boron concentration in each fraction was measured with inductively coupled plasma atomic emission spectroscopy. Obtained results revealed that sodium borocaptate and boronophenylalanine were associated with different rates of boron uptake in different phases. 

The earliest methods for tin analysis, namely, gravimetric and titrimetric methods, are now mainly of historical interest. Being essentially macro methods, laborious in application, they are limited and mainly useful for levels of tin in food in the 50-100 ppm range or above. The use of colorimetric analysis is associated with problems of specificity, sensitivity, and stability of the tin complexes formed. Nowadays, methods for tin analysis in biological media include the various atomic spectroscopic techniques (atomic absorption spectrometry, atomic emission spectroscopy, and inductively coupled plasma atomic emission spectrometry) as well as electrochemical and neutron activation procedures. 

CNAA neutron activation analysis with preirradiation separation ETAAS electrothermal atomic absorption spectrometry EXAFS extended X-ray absorption fine-structure spectroscopy ICPAES inductively coupled plasma atomic emission spectrometry IGF-II immunoglobulin factor II... 

Silicones have been extracted from environmental samples with solvents such as hexane, diethyl ether, methyl isobutylketone, ethyl acetate, and THF, using either sequential or Soxhlet techniques (690-695). Silicones of a wide range of molecular weights and polarities are soluble in THF. This feature, coupled with its volatility and miscibility with water, makes THF an excellent solvent for the extraction of silicones from wet samples, ie, soils and sediments. Trace levels of silicones extracted from environmental samples have been measured by a number of techniques, including atomic absorption spectroscopy (AA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), pyrolysis GC-MS, as well as H and Si NMR spectroscopy (674,684,692,696-700). The use of separation techniques, such as gel permeation and high pressure liquid chromatography interfaced with sensitive, silicon-specific AA or ICP detectors, has been particularly advantageous for the analysis of silicones in environmental extracts (685,701-704). 

Lead detection kits are useful as a quick check for screening areas for lead abatement. A positive response is evidence of the presence of lead or a positive interference. A negative response, however, is not conclusive evidence of the absence of lead. The test provides presumptive evidence for the presence of lead, not its absence. A more thorough determination may need to be performed by a quantitative laboratory analysis of any representative bulk material available to substantiate the absence of lead. Samples are analyzed for lead at OSHA s Salt Lake Technical Center (SLTC) using OSHA methods ID-121 with Atomic Absorption Spectroscopy (AAS), ID-125 G with Inductively Coupled Plasma (ICP), or ID-206 (Solders by ICP). If necessary, lower limits of detection for lead may be achieved using ICP Mass Spectrometer procedures. 

Elemental analysis by atomic emission and mass spectrometry with inductively coupled plasmas is shown by Houk to be the techniques of choice for the analysis of rare earth materials. In this chapter the instrumentation and principles of use of inductively coupled plasmas themselves are outlined as well as their function as a source for atomic emission spectroscopy and mass spectrometry. A number of important applications for which these techniques are eminently suited are also discussed. 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES) the sample must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the (plasma) flame, they must be transported there as gases, as finely dispersed droplets of a solution, or as fine particulate matter. The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter discusses specifically substances that are normally liquids at ambient temperatures. This sort of inlet is the commonest in analytical work. 

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. 

In Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), a gaseous, solid (as fine particles), or liquid (as an aerosol) sample is directed into the center of a gaseous plasma. The sample is vaporized, atomized, and partially ionized in the plasma. Atoms and ions are excited and emit light at characteristic wavelengths in the ultraviolet or visible region of the spectrum. The emission line intensities are proportional to the concentration of each element in the sample. A grating spectrometer is used for either simultaneous or sequential multielement analysis. The concentration of each element is determined from measured intensities via calibration with standards. 

The metal content analysis of the samples was effected by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES Varian Liberty II Instrument) after microwaves assisted mineralisation in hydrofluoric/hydrochloric acid mixture. Ultraviolet and visible diffuse reflectance spectroscopy (UV-Vis DRS) was carried out in the 200-900 nm range with a Lambda 40 Perkin Elmer spectrophotometer with a BaS04 reflection sphere. HF was used as a reference. Data processing was carried out with Microcal Origin 7.1 software. 

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