Atomic emission spectroscopy studies

Atomic emission spectroscopy (AES) studies on these materials show a boron content of approximately 28.8%. Because of the dilution effects of the vinyl/phenyl... 

When the problem has been defined and needed background information has been studied, it is time to consider which analytical methods will provide the data you need to solve the problem. In selecting techniques, you can refer back to the other chapters in this book. For example, if you want to measure the three heavy metals (Co, Fe, and Ni) that were suspect in the Bulging Drum Problem, you might immediately think of atomic absorption or inductively coupled plasma atomic emission spectroscopies and reread Chapter 8 of this book. How would you choose between them Which would be more accurate More precise Does your lab have both instruments Are they both in working order What if you have neither of them What sample preparation would be needed ... 

Atomic emission spectroscopy is one of the oldest instrumental techniques used for chemical analysis. It is used to study the transitions between electronic energy levels in atoms or ions. These energy differences are usually in the visible region (400-700 nm) of the electromagnetic spectrum, but if the energy difference is larger, then the transitions may lie in the ultraviolet region. 

Ultraviolet-visible (UV-Vis) spectrophotometric detectors are used to monitor chromatographic separations. However, this type of detection offers very little specificity. Element specific detectors are much more useful and important. Atomic absorption spectrometry (AAS), inductively coupled plasma-atomic emission spectroscopy (ICPAES) and inductively coupled plasma-mass spectrometry (ICP-MS) are often used in current studies. The highest sensitivity is achieved by graphite furnace-AAS and ICP-MS. The former is used off-line while the latter is coupled to the chromatographic column and is used on-line . 

The ion atmosphere of nucleic acids directly affects measured biochemical and biophysical properties. However, study of the ion atmosphere is difficult due to its diffuse and dynamic nature. Standard techniques available have significant limitations in sensitivity, specificity, and directness of the assays. Buffer exchange-atomic emission spectroscopy (BE-AES) was developed to overcome many of the limitations of previously available techniques. This technique can provide a complete accounting of all ions constituting the ionic atmosphere of a nucleic acid at thermodynamic equilibrium. Although initially developed for the study of the ion atmosphere of nucleic acids, BE-AES has also been applied to study site-bound ions in RNA and protein. 

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and x-ray fluorescence spectrometry (XRFS) are also used for elemental determination in environmental studies, although they are generally less sensitive than ICP-MS techniques. 

Adsorption capacities were studied -by Atomic Emission Spectroscopy (Vista-Pro ICP-OES from VARIAN) for lead analysis and -by UV Spectrometry (Nicolet Evolution 300 from ThermoElectron Corporation) for p-nitrophenol determination. 

Inorganic extractables/leachables would include metals and other trace elements such as silica, sodium, potassium, aluminum, calcium, and zinc associated with glass packaging systems. Analytical techniques for the trace analysis of these elements are well established and include inductively coupled plasma—atomic emission spectroscopy (ICP-AES), ICP-MS, graphite furnace atomic absorption spectroscopy (GFAAS), electron microprobe, and X-ray fluorescence. Applications of these techniques have been reviewed by Jenke. " An example of an extractables study for certain glass containers is presented by Borchert et al. ". ... 

Size exclusion chromatography (SEC) has been used to measure molecular weight (MW) distribution of humic substances (3, 6-9). Coupled with detection methods such as molecular fluorescence spectroscopy and dissolved organic carbon analysis (7), electrochemical detection (9), and atomic emission spectroscopy (5), SEC has been used extensively to study humic-metal complexes. A major disadvantage of SEC is that it does not provide adequate resolution for separating humic materials as they do not appear to be made up of distinct fractions with large differences in MW. 

Emission spectroscopy also utilizes the range of EM spectra, but the sample s emission of EM waves, rather than its absorption is studied. Typically, the sample is allowed to absorb energy and then the resulting emissions are studied. This type of spectroscopy includes plasma emission spectroscopy, atomic emission spectroscopy, and fluorescence spectroscopy. 

The oxidatively adsorbed adlayer of chlorine may be partially reduced to chloride at negative potentials, as shown by LEED and atomic emission spectroscopy (AES) studies... 

The presence of a conserved metal center in AtzA prompted Wackett and co-workers to perform detailed studies on the influence of metals on AtzA activity and the metal content of the native enzyme. AtzA activity was shown to depend on an enzyme-bound, divalent transition-metal ion. The loss of activity obtained by incubating the enzyme with metal chelators was reversible upon addition of Fe Mn or Co salts. The results obtained from inductively coupled atomic plasma emission spectroscopy studies on the native enzyme indicate that there is about one iron atom per subunit. In the absence of an X-ray structure of AtzA, a minimal mechanism was proposed in which the catalytic iron atom is implicated in activating water for direct nucleophilic attack on the atrazine substrate (Figure 19(a)). ... 

Actual metal contents were determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Metal particles were examined by X-ray diffraction, transmission electron microscopy and CO chemisorption. Details about the procedures used can be found elsewhere [9]. In the case of Pd-Ag/C catalysts, the combination of these three techniques enabled us to obtain the metal particles size and their bulk and surface composition [9, 13]. Finally, the Pt/C catalysts were tested for benzene hydrogenation, and the Pd-Ag/C catalysts were used to study mass transfer in the support during a well-known reaction the selective hydrodechlorination of 1,2-diehloroethane into ethylene. 

Spectral interference has been well studied and are probably best understood in atomic emission spectroscopy. The usual remedy to alleviate a spectral interference is to either increase the spectral resolution of the spectrometer (which often is not possible with a given type of instrument) or to select an alternative emission line. Three types of spectral interference can be discriminated 1. Direct wavelength coincidence with another emission line, 2. partial overlap of the hne under study with an interfering line in close proximity, 3. a linear or non-linear increase or decrease in background continuum (see Fig. 12.33). 

The chemical composition of the natural beryl sample used in this study was analyzed by X-ray wavelength dispersive spectroscopy for major atomic contents, inductivity coupled plasma-atomic emission spectroscopy for Be content, and atomic absorption sp>ectroscopy for Li and Rb contents (Table 1). The type I/II H2O contents were determined from intensities of IR bands due to the asymmetric stretching of type I and the symmetric stretching of type II in a polarized IR spectrum at RT (See the spectrum in the next section), using their molar absorption coefficients of 206 L moH cm-i and 256 L moH cm-i. 

CdS and Mn-doped CdS NPs of 2 mnhave been prepared by Dandia et al. [45] at room temperature by a wet chemieal teehnique. The heterogeneous catalysts were fully characterized by XRD, TEM, energy-dispersive X-ray spectroscopy (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), and UVA IS. These NPs were exploited by us to study their catalytic activities towards the chemoselective, aqueous-mediated synthesis of 2-aiyl benzimidazoles (Scheme 5.13). 

For example, the analysis of electronic grade silicon has been studied using atomic emission spectroscopy from inductively coupled plasma and the level of aluminium and phosphorus in such material has also been determined using an indirect atomic... 

We consider the determination of the concentration of elements in various materials studied in agricultural and environmental applications, by the use of the following methods atomic absorption spectroscopy (AAS) using a flame (FAAS) or a graphite furnace (GFAAS) as an atom cell inductively coupled plasma atomic emission spectroscopy (ICPAES) inductively coupled plasma mass spectrometry (ICPMS) and X-ray fluorescence (XRF). The analytical characteristics of the methods as normally practised are compared with the requirements of fitness for purpose in the examination of soils and sediments, waters, dusts and air particulates, and animal and plant tissue. However, there are numerous specialized techniques that cannot be included here. 

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