Spectrometry, emission

New developments are, however, needed to make a major step forward in the field of speciation analysis. The first part, isolation and separation of species, may be the easiest one to tackle. For the second part, the measurement of the trace element, a major improvement in sensitivity is needed. As the concentration of the different species lies far below that of the total concentration (species often occur at a mere ng/1 level and below), it looks like existing methods will never be able to cope with the new demands. A new physical principle will have to be explored, away from absorption spectrometry, emission spectrometry, mass spectrometry, and/or more powerful excitation sources than flame, arc or plasma will have to be developed. The goal is to develop routine analytical set-ups with sensitivities that are three to six orders of magnitude lower than achieved hitherto. 

In 1956 Boyd and Larson thoroughly sought for technetium in various samples using analytical methods of high sensitivity such as neutron activation, mass spectrometry, emission spectroscopy, spectrophotometry, and polarography. Not one of their numerous concentrates revealed traces of natural technetium. It now seems clear that primordial technetium does not exist in nature. 

Atomic Emission Spectrometry. Emission spectroscopy was the earliest developed multielement measurement technique (1 9,50,51, 52). Its widest acceptance was by the metal industry where it was particularly useful in determining a few elements repetitively in a metal (usually some form of steel) matrix which was well defined. It was also used in the food and agricultural field and was responsible for much of the early knowledge of the concentrations of a number of trace elements in orange juice (23, 2k). 

Main reaction products from 308 nm photolysis of 92 naphthalene identified by mass spectrometry Emission cross-sections of excited fragments from the 493 electron impact dissociation of SiH4, SiD, Si2H, and GeH4... 

Spectrophotometers came into widespread use beginning around 1940, and this led to wide application in petroleum analysis. Ultraviolet absorption spectroscopy, infrared spectroscopy, mass spectrometry, emission spectroscopy, and nuclear magnetic resonance spectroscopy continue to make major contributions to petroleum analysis. 

Most optical detection methods for biosensors are based on ultra-violet (UV) absorption spectrometry, emission spectroscopic measurement of fluorescence and luminescence, and Raman spectroscopy. However, surface plasmon resonance (SPR) has quickly been widely adopted as a nonlabeling technique that provides attractive advantages. Fueled by numerous new nanomateiials, their unique, SPR-based or related detection techniques are increasingly being investigated [28-31]. 

Barium at concentrations > 1 mg P is determined by flame spectrometry (emission is measured in the region of 489 nm) after being first concentrated by precipitation with calcium in the form of carbonate [16]. 

Source Optical spectrometry emission absorption fluorescence Mass spectrometry... 

Spark source mass spectrometry Emission spectrometry 98 + 11 21.5 + 1.9... 

Elemental Analysis Atomic absorption spectrometry X-Ray fluorescence spectrometry Plasma emission spectrometry... 

From J. A. Dean and T. C. Rains, Standard Solutions for Flame Spectrometry, in Flame Emission and Atomic Absorption Spectrometry, J. A. Dean and T. C. Rains (Eds.), Vol. 2, Chap. 13, Marcel Dekker, New York, 1971. 

The section on Spectroscopy has been retained but with some revisions and expansion. The section includes ultraviolet-visible spectroscopy, fluorescence, infrared and Raman spectroscopy, and X-ray spectrometry. Detection limits are listed for the elements when using flame emission, flame atomic absorption, electrothermal atomic absorption, argon induction coupled plasma, and flame atomic fluorescence. Nuclear magnetic resonance embraces tables for the nuclear properties of the elements, proton chemical shifts and coupling constants, and similar material for carbon-13, boron-11, nitrogen-15, fluorine-19, silicon-19, and phosphoms-31. 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES) the sample must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the (plasma) flame, they must be transported there as gases, as finely dispersed droplets of a solution, or as fine particulate matter. The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter discusses specifically substances that are normally liquids at ambient temperatures. This sort of inlet is the commonest in analytical work. 

Confusingly, FAB is sometimes called secondary ion mass spectrometry (SIMS), the secondary referring to the nature of the process (primary bombardment, secondary emission), but see next item. 

In the case of fast ions, the terminology of secondary ion emission mass spectrometry (SIMS) is more obvious in that a primary incident beam of ions onto a target releases secondary ions after impact. 

Figure 8.30 K emission spectrum of tin. The ] and P2 lines are at 0.491 A and 0.426 A, respectively. (Reproduced, with permission, from Jenkins, R., An Introduction to X-ray Spectrometry, p. 22, Hey den, London, 1976)...

Elemental chemical analysis provides information regarding the formulation and coloring oxides of glazes and glasses. Energy-dispersive x-ray fluorescence spectrometry is very convenient. However, using this technique the analysis for elements of low atomic numbers is quite difficult, even when vacuum or helium paths are used. The electron-beam microprobe has proven to be an extremely useful tool for this purpose (106). Emission spectroscopy and activation analysis have also been appHed successfully in these studies (101). 

Analyses of alloys or ores for hafnium by plasma emission atomic absorption spectroscopy, optical emission spectroscopy (qv), mass spectrometry (qv), x-ray spectroscopy (see X-ray technology), and neutron activation are possible without prior separation of hafnium (19). Alternatively, the combined hafnium and zirconium content can be separated from the sample by fusing the sample with sodium hydroxide, separating silica if present, and precipitating with mandelic acid from a dilute hydrochloric acid solution (20). The precipitate is ignited to oxide which is analy2ed by x-ray or emission spectroscopy to determine the relative proportion of each oxide. 

Inductively coupled plasma (icp) emission, direct current plasma (dcp), and inductively coupled plasma mass spectrometry (icp/ms) have taken over as the methods of choice for the simultaneous detection of metallic impurities in hafnium and hafnium compounds (29,30). 

Fig. 4. Examples of emission spectrometry as a diagnostic monitoring tool for plasma processing, (a) The removal of chlorine contamination from copper diode leads using a hydrogen—nitrogen plasma. Emissions are added together from several wavelengths, (b) The etching and eventual removal of a 50-p.m thick polyimide layer from an aluminum substrate, where (x ) and (° ) correspond to wavelengths (519.82 and 561.02 nm, respectively) for molecular CO2...

Qualitative. The classic method for the quaUtative determination of silver ia solution is precipitation as silver chloride with dilute nitric acid and chloride ion. The silver chloride can be differentiated from lead or mercurous chlorides, which also may precipitate, by the fact that lead chloride is soluble ia hot water but not ia ammonium hydroxide, whereas mercurous chloride turns black ia ammonium hydroxide. Silver chloride dissolves ia ammonium hydroxide because of the formation of soluble silver—ammonia complexes. A number of selective spot tests (24) iaclude reactions with /)-dimethy1amino-henz1idenerhodanine, ceric ammonium nitrate, or bromopyrogaHol red [16574-43-9]. Silver is detected by x-ray fluorescence and arc-emission spectrometry. Two sensitive arc-emission lines for silver occur at 328.1 and 338.3 nm. 

Highly sensitive iastmmental techniques, such as x-ray fluorescence, atomic absorption spectrometry, and iaductively coupled plasma optical emission spectrometry, have wide appHcation for the analysis of silver ia a multitude of materials. In order to minimize the effects of various matrices ia which silver may exist, samples are treated with perchloric or nitric acid. Direct-aspiration atomic absorption (25) and iaductively coupled plasma (26) have silver detection limits of 10 and 7 l-lg/L, respectively. The use of a graphic furnace ia an atomic absorption spectrograph lowers the silver detection limit to 0.2 l-ig/L. 

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