Quantitative atomic emission spectrometry

The intensity of an elemental atomic or ion line is used as the analytical signal in quantitative atomic emission spectrometry. In fact, the intensities are unequivo-... 

Several instmmental methods are available for quantitative estimation of from moderate to trace amounts of cerium in other materials. X-ray fluorescence is widely available, versatile, and suitable for deterrninations of Ce, and any other Ln, at percent levels and lower in minerals and purer materials. The uv-excited visible luminescence of cerium is characteristic and can be used to estimate Ce content, at ppm levels, in a nonluminescing host. X-ray excited optical luminescence (15), a technique especially appropriate for Ln elements including cerium, rehes on emissions in the visible, and also measures ppm values. Atomic emission spectrometry is appHcable to most lanthanides, including Ce (16). The precise lines used for quantitative measurement must be chosen with care, but once set-up the technique is suitable for routine analyses. 

Instrumentation. Flame Characteristics. Flame Processes. Emission Spectra. Quantitative Measurements and Interferences. Applications of Flame Photometry and Flame Atomic Emission Spectrometry. 

D. A. Sadler and D. Littlejohn, Use of multiple emission lines and principal component regression for quantitative analysis in inductively coupled plasma atomic emission spectrometry with charge coupled device detection, J. Anal. At. Spectrom., 11, 1996, 1105-1112. 

In the test method, the coal or coke to be analyzed is ashed under controlled conditions, digested by a mixture of aqua regia and hydrofluoric acid, and finally dissolved in 1% nitric acid. The concentration of individual trace elements is determined by either inductively coupled plasma-atomic emission spectrometry (ICPAES) or inductively coupled plasma-mass spectrometry (ICPMS). Selected elements that occur at concentrations below the detection limits of ICPAES can be analyzed quantitatively by graphite furnace atomic absorption spectrometry (GFAA). 

Inductively coupled plasma-atomic emission spectrometry was investigated for simultaneous multielement determinations in human urine. Emission intensities of constant, added amounts of internal reference elements were used to compensate for variations in nebulization efficiency. Spectral background and stray-light contributions were measured, and their effects were eliminated with a minicomputer-con-trolled background correction scheme. Analyte concentrations were determined by the method of additions and by reference to analytical calibration curves. Internal reference and background correction techniques provided significant improvements in accuracy. However, with the simple sample preparation procedure that was used, lack of sufficient detecting power prevented quantitative determination of normal levels of many trace elements in urine. 

The history of atomic emission spectrometry (AES) goes back to Bunsen and Kirchhoff, who reported in 1860 on spectroscopic investigations of the alkali and alkali earth elements with the aid of their spectroscope [1], The elements cesium and rubidium and later on thorium and indium were also discovered on the basis of their atomic emission spectra. From these early beginnings qualitative and quantitative aspects of atomic spectrometry were considered. The occurrence of atomic spectral lines was understood as uniequivocal proof of the presence of these elements in a mixture. Bunsen and Kirchhoff in addition, however, also estimated the amounts of sodium that had to be brought into the flame to give a detectable line emission and therewith gave the basis for quantitative analyses and trace determinations with atomic spectrometry. 

Atomic spectroscopy is the oldest instrumental elemental analysis principle, the origins of which go back to the work of Bunsen and Kirchhoff in the mid-19th century [1], Their work showed how the optical radiation emitted from flames is characteristic of the elements present in the flame gases or introduced into the burning flame by various means. It had also already been observed that the intensities of the element-specific features in the spectra, namely the atomic spectral lines, changed with the amount of elemental species present. Thus the basis for both qualitative and quantitative analysis with atomic emission spectrometry was discovered. These discoveries were made possible by the availability of dispersing media such as prisms, which allowed the radiation to be spectrally resolved and the line spectra of the elements to be produced. 

Instrumentation. Flame characteristics. Flame processes. Emission spectra. Quantitative measurements and interferences. Applicaiion.s of flame photometry and flame atomic emission spectrometry. 

This chapter deals with optical atomic, emission spectrometry (AES). Generally, the atomizers listed in Table 8-1 not only convert the component of samples to atoms or elementary ions but, in the process, excite a fraction of these species to higher electronic stales.. 4, the excited species rapidly relax back to lower states, ultraviolet and visible line spectra arise that are useful for qualitative ant quantitative elemental analysis. Plasma sources have become, the most important and most widely used sources for AES. These devices, including the popular inductively coupled plasma source, are discussedfirst in this chapter. Then, emission spectroscopy based on electric arc and electric spark atomization and excitation is described. Historically, arc and spark sources were quite important in emission spectrometry, and they still have important applications for the determination of some metallic elements. Finally several miscellaneous atomic emission source.s, including jlanies, glow discharges, and lasers are presented. 

The determination of iodine in seawater helps in understanding the marine environment. A variety of analytical methods have been proposed for the quantitative determination of iodine in seawater. This chapter discusses the methods employed for the separation and determination of iodine in seawater. These methods include capillary electrophoresis (CE), ion chromatography (IC), high-performance hquid chromatography (HPLC), gas chromatography (GC), spectrophotometry, ion-selective electrode, polar-ography, voltammetry, atomic emission spectrometry (AES), and neutron activation analysis (NAA). The advantages and hmitations of these methods are also assessed and discussed. Since iodine is present in the ocean at trace levels and the matrices of seawater are complex, especially in estuarine and coastal waters, the methods developed for the... 

ABSTRACT A method has been developed for accurate quantitative detetmination of additive elements and wear metals in gasoline and diesel fuel in the concentration range of 0 to SO ppm using inductively coupled plasma atomic emission spectrometry (ICP-AES). This method requires an ICP capable of detecting metals at the 0.02 mg/kg level, and capable of linear calibration over the range of O.OS to 20.0 mg/kg with a correlation coefficient of 0.9999 or better. No additional ICP-AES accessoiy or lengthy sample preparation is required. The PerkinElmer Optima 4300 has been shown to meet this requirement. 

Quantitative analysis Flame photometry is used for the quantitative determination of alkaline metals and alkaline-earth metals in blood, serum, and urine in clinical laboratories. It provides much simpler spectra than those found in other types of atomic emission spectrometry, but its sensitivity is much reduced. 

The human eye is a useful detector for qualitative analysis but not for quantitative analysis. Replacing the human eye with a spectrometer and photon detector such as a PMT or CCD permits more accurate identification of the elements present because the exact wavelengths emitted by the sample can be determined. In addition, the use of a photon detector permits quantitative analysis of the sample. The wavelength of the radiation indicates what element is present, and the radiation intensity indicates how much of the element is present. Flame atomic emission spectrometry is particularly useful for the determination of the elements in the first two groups of the periodic table, including sodium, potassium, lithium, calcium, magnesium, strontium, and barium. The determination of these elements is often called for in medicine, agriculture, and animal science. Remember that the term spectrometry is used for quantitative analysis by the measurement of radiation intensity. 

The solvent and other elements present in the sample cause matrix effects. These affect atomization efficiency, ionization efficiency, and therefore the strength of the MS signal. This directly impacts quantitative results. Signals may be suppressed or enhanced by matrix effects. Aqueous solutions act very differently from organic solvents, which in turn act differently from each other. The problem can be overcome for the most part by matrix matching (i.e., the standards used for calibration are matched for acid concentration, major elements, viscosity, etc. to the matrix of the samples being analyzed). This is similar to atomic absorption and atomic emission spectrometry where the same requirement in matching solvent and predominant matrix components is required for accurate quantitative analysis. The use of internal standards will also compensate for some matrix effects and will improve the accuracy and precision of ICP-MS measurements. 

Application of Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) to Metal Quantitation and Speciation in Synfuels... 

Initially hydride generation and cold vapour techniques were developed for the quantitative determination of the hydride-forming elements and mercury by atomic absorption spectrometry (Chapters, Sections 6.2 and 6.3), but nowadays these methods are also widely used in plasma atomic emission spectrometry. In the hydride generation technique, hydride-forming elements are more efficiently transported to the plasma than by conventional solution nebulization, and the production and excitation of free atoms and ions in the hot plasma is therefore more efficient. Spectral interferences are also reduced when the analyte is separated from the elements in the sample matrix. Both continuous (FIA) and batch approaches have been used for hydride generation. The continuous method is more frequently used in plasma AES than in AAS. Commercial hydride generation systems are available for various plasma spectrometers. 

Elemental analyses, involving an impressive array of nondestructive spectroscopic methods or decomposition of the material and analyses by AAS (atomic absorption spectrometry) or ICP-AES (inductively coupled plasma atomic emission spectrometry), form a very important complement to mineralogical analyses as outlined by Boyle (this volume), Korsman et al. (this volume), Amonette Sanders (1994), Sawhney Stilwell (1994), Hawthorne (1988), Fairchild et al. (1988), and Stone (1982). However, these elemental techniques are not intended to provide a qualitative or quantitative assessment of the mineralogy of a deposit. 

Hydride generation techniques are superior to direct solution analysis in several ways. However, the attraction offered by enhanced detection limits is offset by the relatively few elements to which the technique can be applied, potential interferences, as well as limitations imposed on the sample preparation procedures in that strict adherence to valence states and chemical form must be maintained. Cold-vapor generation of mercury currently provides the most desirable means of quantitation of this element, although detection limits lower than AAS can be achieved when it is coupled to other means of detection (e.g., nondispersive atomic fluorescence or micro-wave induced plasma atomic emission spectrometry). 

See also Amperometry. Atomic Emission Spectrometry Flame Photometry. Chemiiuminescence Overview Liquid-Phase. Flow Injection Analysis Principles. Fluorescence Quantitative Analysis. Ion Exchange Ion Chromatography Instrumentation. Liquid Chromatography Overview. Ozone. Sampling Theory. Sulfur. Textiles Natural Synthetic. 

This technique comprises a group of quantitative instrumental analytical methods based on the capacity of free atoms of both emitting and absorbing radiation at a specific wavelength. The radiation lies within the range for ultraviolet and visible light. A distinction is made between atomic emission spectrometry (AES), atomic absorption spectrometry (AAS), and atomic fluorescence spectrometry. The most commonly applied techniques are flame-AAS, graphite furnace-AAS, and ICP-AES. With ICP, excitation takes place in a plasma at a temperature of 7000 K. 

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