Volatilization atomic spectroscopy

Chemical Analysis. The presence of siUcones in a sample can be ascertained quaUtatively by burning a small amount of the sample on the tip of a spatula. SiUcones bum with a characteristic sparkly flame and emit a white sooty smoke on combustion. A white ashen residue is often deposited as well. If this residue dissolves and becomes volatile when heated with hydrofluoric acid, it is most likely a siUceous residue (437). Quantitative measurement of total sihcon in a sample is often accompHshed indirectly, by converting the species to siUca or siUcate, followed by deterrnination of the heteropoly blue sihcomolybdate, which absorbs at 800 nm, using atomic spectroscopy or uv spectroscopy (438—443). Pyrolysis gc followed by mass spectroscopic detection of the pyrolysate is a particularly sensitive tool for identifying siUcones (442,443). This technique rehes on the pyrolytic conversion of siUcones to cycHcs, predominantly to [541-05-9] which is readily detected and quantified (eq. 37). 

Characteristic Masses for Identification of Additional Organic Pollutants (Not Listed in the Text) by GC/MS Volatility of Some Additional Organic Substances (Not Listed in Text) for Purge and Trap Analysis Analysis of Elements by Atomic Spectroscopy ... 

The methods of atomic spectroscopy, important in the first decades of the twentieth century, again played a significant role in the 1960s as a result of new inventions (Table 1.3). Development of atomic absorption, in particular with graphite furnace atomization, resulted in new procedures that could measure down to the 10 % level. Somewhat lower concentrations could be determined with generation of volatile compounds, in particular hydrides however, this was restricted to only a few elements. The development of atomization and excitation in... 

Spectroscopic determination of atomic species can only be performed on a gaseous medium in which the individual atoms or elementary ions, such as Fe, Mg, or Al, are well separated from one another. Consequently, the first step in all atomic spectroscopic procedures is atomization, a process in which a sample is volatilized and decomposed in such a way as to produce gas-phase atoms and ions. The efficiency and reproducibility of the atomization step can have a large influence on the sensitivity, precision, and accuracy of the method. In short, atomization is a critical step in atomic spectroscopy. 

Ammonium-l-pyrrolidinecarbodithiolate (APDC) A protective agent in atomic spectroscopy that forms volatile species with an analyte. 

Protective agent In atomic spectroscopy, species that form soluble complexes with the analyte and thereby prevent the formation of compounds that have low volatility. 

The most common approach taken in utilizing the hydrides for analysis is to permit the reaction to proceed for some time, holding the volatile species in a balloon attached to the system. When the reaction is complete, the hydride is analyzed by flame atomic spectroscopy. This general method has been used to determine parts-per-billion levels of arsenic and selenium in water 165-170) and to determine antimony, arsenic, and selenium using an automated system (777). Thompson and Thomerson (772) have used a sodium borohydride solution to convert various ionic forms of arsenic, bismuth, antimony, selenium, tin. 

A. Lopez-Molinero, D. Sipiera and J. R. Castillo, Enhanced vaporization of volatile halide of antimony(lII) for sample introduction in atomic spectroscopy kinetic mechanism, J. Anal. At. Spectrom., 2011, 26(9), 1841-1848. 

Spectroscopic determination of atomic species can only be carried out in the gas phase, where the individual atoms or ions are well separated. Consequently, the first step in the process is atomization, where the sample is volatilized (heated to the gas phase) and decomposed to produce an atomic gas. The differences between the various atomic spectroscopy techniques available, largely lie in the different ways of doing this. The most widely used method is flame atomization, where the sample is decomposed in a flame (a sophisticated version of the common flame test), but other common methods (Table 5.2) are... 

The neutral surfactant is measured after fixing of the ionic substances on a combined anionic/cationic ion exchange column. Volatile substances in the eluate are determined by gas chromatography and nonvolatile substances are measured gravimetrically. In the bulk of the neutral compounds phosphoric acid triesters may be present. This part is additionally determined by atom emission spectroscopy. 

Tin compounds are converted to the corresponding volatile hydride (SnH4, CH3 SnH3, (CH3 )2 SnH2, and (CH3 >3 SnH) by reaction with sodium borohydride at pH 6.5 followed by separation of the hydrides and then atomic absorption spectroscopy using a hydrogen-rich hydrogen-air flame emission type detector (Sn-H band). 

Siliceous materials—Si, Al, Fe, Ti, Ca, Mg, Na, K, Mn, Ni, Ba, Ag, Au, Ca, Cr, Cu, Ga, In, Mo, Sb and Zn—may be analyzed by a lithium tetraborate fusionr-acid dissolution technique using atomic absorption spectroscopy. Mercury, tin, and lead volatilize by this technique, and gold and silver in concentrations above 0.5 wt% cannot be held in solution. Coal ash is preconcentrated prior to analysis, and there is possible silica interference. Analytical results, where possible, are compared statistically with other reported values. 

Mass balance measurements for 41 elements have been made around the Thomas A. Allen Steam Plant in Memphis, Tenn. For one of the three independent cyclone boilers at the plant, the concentration and flow rates of each element were determined for coal, slag tank effluent, fly ash in the precipitator inlet and outlet (collected isokinetically), and fly ash in the stack gases (collected isokinetically). Measurements by neutron activation analysis, spark source mass spectroscopy (with isotope dilution for some elements), and atomic adsorption spectroscopy yielded an approximate balance (closure to within 30% or less) for many elements. Exceptions were those elements such as mercury, which form volatile compounds. For most elements in the fly ash, the newly installed electrostatic precipitator was extremely efficient. 

The GC detector compares favorably with atomic absorption and emission spectroscopy in that the sample is completely volatilized and relatively free of matrix effects,... 

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