Spectrometry flame emission

Atomic spectrometry is widely used in many laboratories, particularly whenever trace element analyses are required. Environmental samples are analyzed for heavy-metal contamination, and pharmaceutical samples may be analyzed for metal impurities. The steel industry needs to determine minor components, as well as major ones. The particular technique used wiU depend on the sensitivity required, the number of samples to be analyzed, and whether single-element or multielement measurements are needed. The following discussion gives the capabilities of the techniques. 

In this technique, formerly called flame photometry, the source of excitation energy is a flame. This is a low-energy source, and so the emission spectrum is simple and 

In flame emission, we measure Ca°. In atomic absorption, we measure Ca°. 

The intensity of emission is directly proportional to the concentration of the analyte in the solution being aspirated. So a calibration curve of emission intensity as a function of concentration is prepared. 

As indicated in the figure, side reactions in the flame may decrease the population of free atoms and hence the emission signal. These will be discussed in Section 17.3. 

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Atomic Absorption/Emission Spectrometry. Atomic absorption or emission spectrometric methods are commonly used for inorganic elements in a variety of matrices. The general principles and appHcations have been reviewed (43). Flame-emission spectrometry allows detection at low levels (10 g). It has been claimed that flame methods give better reproducibiHty than electrical excitation methods, owing to better control of several variables involved in flame excitation. Detection limits for selected elements by flame-emission spectrometry given in Table 4. Inductively coupled plasma emission spectrometry may also be employed. 

Table 4. Elemental Detection Limits by Flame Emission Spectrometry ...

Flame atomic absorption spectrometry Flame emission spectrometry... 

Applications Atomic emission spectrometry has been used for polymer/additive analysis in various forms, such as flame emission spectrometry (Section 8.3.2.1), spark source spectrometry (Section 8.3.2.2), GD-AES (Section 8.3.2.3), ICP-AES (Section 8.3.2.4), MIP-AES (Section 8.3.2.6) and LIBS. Only ICP-AES applications are significant. In hyphenated form, the use of element-specific detectors in GC-AED (Section 4.2) and PyGC-AED deserves mentioning. 

Principles and Characteristics Flame emission instruments are similar to flame absorption instruments, except that the flame is the excitation source. Many modem instruments are adaptable for either emission or absorption measurements. Graphite furnaces are in use as excitation sources for AES, giving rise to a technique called electrothermal atomisation atomic emission spectrometry (ETA AES) or graphite furnace atomic emission spectrometry (GFAES). In flame emission spectrometry, the same kind of interferences are encountered as in atomic absorption methods. As flame emission spectra are simple, interferences between overlapping lines occur only occasionally. 

FES Flame emission spectrometry GC-SNIFF Sniffing port gas chromatography... 

Flame emission spectrometry is used extensively for the determination of trace metals in solution and in particular the alkali and alkaline earth metals. The most notable applications are the determinations of Na, K, Ca and Mg in body fluids and other biological samples for clinical diagnosis. Simple filter instruments generally provide adequate resolution for this type of analysis. The same elements, together with B, Fe, Cu and Mn, are important constituents of soils and fertilizers and the technique is therefore also useful for the analysis of agricultural materials. Although many other trace metals can be determined in a variety of matrices, there has been a preference for the use of atomic absorption spectrometry because variations in flame temperature are much less critical and spectral interference is negligible. Detection limits for flame emission techniques are comparable to those for atomic absorption, i.e. from < 0.01 to 10 ppm (Table 8.6). Flame emission spectrometry complements atomic absorption spectrometry because it operates most effectively for elements which are easily ionized, whilst atomic absorption methods demand a minimum of ionization (Table 8.7). 

Wright RJ, Stuczynski TI. Atomic absorption and flame emission spectrometry. In Bartels JM (ed.), Methods of Soil analysis Part 3 Chemical Methods. Madison, WI Soil Science Society of America and Agronomy Society of America 1996, pp. 

Fixation, COj, reaction modeling, 43 426-431 Flame emission spectrometry, lithium, 36 54 Flash photolysis, 46 106, 137, 139-140 organometallics, 19 81-83... 

FLAME PHOTOMETRY AND SPECTROMETRY. The basic principle of flame emission spectrometry rests on the fact that salts of metals, when introduced under carefully coni rolled condiiions imo a suitable flame, are vaporized and excited to emit radiations that are characteristic for each clement. Correlation of the emission intensity with the concentration of that clement forms the basis of quantitative evaluation. 

International Standard Organization. 1993. Water quality. Determination of sodium and potassium. Part 3 Determination of sodium and potassium by flame emission spectrometry. ISO 9964-3. International Organization for Standardization, Case Postale 56, CH-1211, Geneva 20 Switzerland. 

Johnson KE, Yerhoff FW, Robinson J, et al. 1983. Determination of barium at ng ml 1 levels by flame emission spectrometry after ion-exchange separation from 1000-fold amounts of calcium. 

So far in this chapter, absorption techniques have been considered in preference to emission techniques, in spite of the much longer history of flame emission spectrometry (FES).5 This is deliberate, and reflects the far greater relative importance of AAS as a routine technique in most modern environmental... 

Flame Spectrometry in Environmental Chemical Analysis A Practical Guide is a simple, user-friendly guide to safe flame spectrometric methods for environmental samples. It explains key processes involved in achieving accurate and reliable results in atomic absorption spectrometry, atomic fluorescence spectrometry and flame emission spectrometry, showing the inter-relationship of the three techniques, and their relative importance. 

A 250 mL sample of each solution from the polyethylene bottle was filtered through a Millipore filter (0.45 urn pore size). The concentrations of chloride, nitrate and sulfate ions in the filtrate were determined by ion chromatography using a YEW IC 100 of Yokogawa Hokushin Electric Co. Ltd. The concentrations of sodium and potassium were determined by flame emission spectrometry and concentrations of calcium and magnesium by atomic absorption spectrometry using a Hitachi 170-50 Atomic Absorption Spectrophotometer. An aliquot of each filtrate was used for the determination of Sr by ICP emission spectrometry after adding nitric acid (0.1 N), detailed analytical conditions of which are reported elsewhere (3). 

It is clear then that the chemical flame is an effective means by which a free, neutral atom population may be produced from a sample solution for analysis by atomic absorption spectrometry. The fact that flames were inherited from the older technique of flame emission spectrometry may account in part for their popularity, although they also have the following advantages for use in AAS ... 

A flame emission spectrometer therefore consists of an atom source, a monochromator and detector and is therefore simpler instrumentally than the corresponding atomic absorption system. Particular developments engendered by atomic absorption have restimulated interest in flame emission spectrometry after a dormant period. Chief of these is the use of the nitrous oxide—acetylene flame which is sufficiently hot to stimulate thermal atomic-emission from a wide range of metal elements. 

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