Optical-flame spectroscopy

Analysis by atomic (or optical) emission spectroscopy is based on the study of radiation emitted by atoms in their excited state, ionised by the effect of high temperature. All elements can be measured by this technique, in contrast to conventional flames that only allow the analysis of a limited number of elements. Emission spectra, which are obtained in an electron rich environment, are more complex than in flame emission. Therefore, the optical part of the spectrometer has to be of very high quality to resolve interferences and matrix effects.-... 

In flame spectroscopy, the residence time of analyte in the optical path is < 1 s as it rises through the flame. A graphite furnace confines the atomized sample in the optical path for several seconds, thereby affording higher sensitivity. Whereas 1—2 mL is the minimum volume of solution necessary for flame analysis, as little as 1 pL is adequate for a furnace. Precision is rarely better than 5-10% with manual sample injection, but automated injection improves reproducibility to —1%. 

Commission on spectrochemical and other optical procedures for analysis, nomenclature, symbols, units and their usage in spectrochemical analysis. I. General atomic emission spectroscopy. II. Data interpretation. III. Analytical flame spectroscopy and associated procedures, Spectrochim. Acta, 33B, 219, 1978. 

Note NA = not applicable FID = flame ionization detector DOAS = differential optical absorption spectroscopy. 

Potassium has been studied in stellar optical spectra. The famous red K lines at 7663 and 7697 A have been used. This pair of lines played a role in the history of K flame spectroscopy. As nucleosynthesis progressed the galactic K/H abundance ratio innewly born observed stars increased from 10 3 of solar in some early stars to a bitin excess of solar K/H today. If compared instead to Mg, the ratio K/Mg remains near the solar ratio in stars of all metallicities. This is understood as the coproduction of K and Mg in massive Type II supernovae. 

The most utilized methods include X-ray fluorescence (XRF), atomic absorption spectroscopy (AAS), activation analysis (AA), optical emission spectroscopy (OES) and inductively coupled plasma (ICP), mass spectroscopy (MS). Less frequently used techniques include ion-selective electrode (ISE), proton induced X-ray emission (PIXE), and ion chromatography (IC). In different laboratories each of these methods may be practiced by using one of several optional approaches or techniques. For instance, activation analysis may involve conventional thermal neutron activation analyses, fast neutron activation analysis, photon activation analysis, prompt gamma activation analysis, or activation analysis with radio chemical separations. X-ray fluorescence options include both wave-length and/or energy dispersive techniques. Atomic absorption spectroscopy options include both conventional flame and flameless graphite tube techniques. 

A number of methods exist for the determination of parts-per-billion (ng/g) levels of chromium in aqueous media (Table 8.1). These are repeatedly reviewed as new techniques are introduced (4,5,6). Potentially all these techniques could be applied to petroleum samples after matrix destruction, but in practice, only a few have been utilized. After wet oxidation of a large sample (> 100 g), 10 to 50 fig of chromium may be determined by a colorimetric procedure with 1,5-diphenylcarbohydrazide after iron, copper, molybdenum, and vanadium are extracted as the cup-ferrates (3). In survey analyses, Cr levels as low as 5 ng/g have been measured by optical emission spectroscopy after ashing (2,3) or directly by neutron activation with extended irradiation and counting times (1). Concentrations of chromium above 100 ng/g in used lubricating oils have been measured directly by flame atomic absorption (8) for lower concentrations, heated vaporization atomic absorption (HVAA) has been utilized (9). In the Trace Metals Project, two procedures using this latter technique were evaluated for the determination of 10 ng Cr/g in a variety of petroleum matrices. 

Numerous methods for determining macro concentrations of molybdenum are available. Optical emission spectroscopy has been used in survey-type analyses (2), but it does not have adequate sensitivity to measure part-per-billion levels. X-ray fluorescence has been applied for part-per-million levels but cannot be readily extended to the lower levels of interest to the Project. Kinetic methods (3) and colorimetry with suitable pre-concentration (4) are capable of measuring part-per-billion levels of molybdenum but have not been applied to petroleum analysis. Molybdenum has been determined by atomic absorption techniques in such materials as sea water, biological tissue, and soils (5,6,7), Although a procedure for determining metals including molybdenum in petroleum by atomic absorption has been reported (8), no actual data are given for molybdenum. Flame and heated vaporization atomic absorption of aqueous solutions of ashed samples were selected by the Project for concurrent study in two separate laboratories. 

As mentioned earlier, optical atomic spectroscopy is only able to analyze solution sample. As a result, ceramic powders to be tested should be made into solution. The solution is then broken into line droplets and vaporized into individual atoms by heating, which is the step critical to the precision and accuracy of the analysis. Flame is generally used to vaporize the solution, which is therefore also known as flame atomic absorption spectrometry or flame AA. 

For the analysis of ceramic powders by optical atomic specfroscopy, a portion of the powder has to be converted into individual atoms. In practice, this is achieved by dissolving the powder in a liquid to form a solution, which is then broken into fine droplets and vaporized into individual atoms by heating. The precision and accuracy of optical atomic spectroscopy are critically dependent on this step. Vaporization is most commonly achieved by introducing droplets into a flame (referred to as flame atomic absorption spectrometry or flame AA). Key problems with flame AA include incomplete dissociation of the more refractory elements (e.g., B, V, Ta, and W) in the flame and difficulties in determining elements that have resonance lines in the far ultraviolet region (e.g., P, S, and the halogens). While flame AA is rapid, the instruments are rarely automated to permit simultaneous analysis of several elements. 

Soluble Cr(VI), Fe(II), and U(VI) were monitored spectrophotometrically, Cr at 540 nm using the s-diphenyl carbazide method (Bartlett James, 1979), Fe(II) at 562 nm using the ferrozine assay (Stookey, 1970), and U at 575 nm using 2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol (Johnson Florence, 1971). Total dissolved Cr, U, and Fe were determined by flame atomic absorption spectroscopy (AAS) or by inductively coupled plasma (ICP) optical emission spectroscopy. 

Cu 2,000 Hepatic cirrhosis, renal, neurological, gastrointestinal problems Electrical wiring, pipes, fungicides, algicides, insecticides, fertilizers 0.02-0.1 pg/1 by ICP-MS 0.3 pg/1 by ICP-optical emission spectroscopy 0.5 pg/1 by flame AAS... 

Optical emission spectroscopy includes the observation of flame-, arc-, and spark-induced emission phenomena in the ultraviolet, visible, and near infrared regions of the electromagnetic spectrum [38]. Qualitative and quantitative information can be gained from the intensity of the characteristic emission wavelengths. Analysis of lead in environmental samples (e.g., soils, rocks, and minerals) may be performed reproducibly down to the 5 ppm level. Emission spectroscopy is best used for the multi-elemental analysis of samples, because of the high cost of equipment. Usually, single element analyses are not performed on a emission spectrograph. 

Numerous methods have been pubUshed for the determination of trace amounts of tellurium (33—42). Instmmental analytical methods (qv) used to determine trace amounts of tellurium include atomic absorption spectrometry, flame, graphite furnace, and hydride generation inductively coupled argon plasma optical emission spectrometry inductively coupled plasma mass spectrometry neutron activation analysis and spectrophotometry (see Mass spectrometry Spectroscopy, optical). Other instmmental methods include polarography, potentiometry, emission spectroscopy, x-ray diffraction, and x-ray fluorescence. 

The detection and determination of traces of cobalt is of concern in such diverse areas as soflds, plants, fertilizers (qv), stainless and other steels for nuclear energy equipment (see Steel), high purity fissile materials (U, Th), refractory metals (Ta, Nb, Mo, and W), and semiconductors (qv). Useful techniques are spectrophotometry, polarography, emission spectrography, flame photometry, x-ray fluorescence, activation analysis, tracers, and mass spectrography, chromatography, and ion exchange (19) (see Analytical TffiTHODS Spectroscopy, optical Trace and residue analysis). 

Fick s law 592 Filter funnel 102 Filter papers 115 folding of, 116 incineration of, 120, 121 macerated, 450 quantitative, (T) 116 Filter pulp 450 Filtering crucibles 102 Filters, optical 661 Filtration 102, 106, 115 accelerated, 450 technique of, 116, 117 with filter papers, 116 with filtering crucibles, 117 Flame emission spectroscopy 779, 797 background correction, 795 elementary theory of, 780 D. of alkali metals by, 812... 

Analysis. Ca gives a brick-red flame coloration, indicating that various optical spectroscopies will be effective in its determination. Ca is quantitatively determined by colorimetry down to 100 ppb using murexide or o-cresolphthalein, by atomic absorption spectroscopy (AAS) to 20 ppb, to 1 ppb by electrothermal absorption spectroscopy (ETAS), to 0.01 ppb by inductively-coupled plasma emission spectroscopy (ICPES), and to 10 ppb by inductively-coupled plasma mass spectroscopy (ICPMS). A spot test for Ca which extends to 3 ppm is provided by glyoxal bis(2-hydroxyanil). 

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