Plasma-atomic emission spectroscopy

Plasma sources were developed for emission spectrometric analysis in the late-1960s. Commercial inductively coupled and d.c. plasma spectrometers were introduced in the mid-1970s. By comparison with AAS, atomic plasma emission spectroscopy (APES) can achieve simultaneous multi-element measurement, while maintaining a wide dynamic measurement range and high sensitivities and selectivities over background elements. As a result of the wide variety of radiation sources, optical atomic emission spectrometry is very suitable for multi-element trace determinations. With several techniques, absolute detection limits are below the ng level. 

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)). ... 

Uden P (1989) Chromatographic detection by atomic plasma emission spectroscopy. In Harrison R, Rapsomanikis S (eds) Environmental Analysis Using Chromatography Interfaced with Atomic Spectroscopy. Ellis Horwood Ltd., Chichester, pp 96-126. 

The principal advantages of interfaced chromatography-atomic plasma emission spectroscopy (C-APES) are ... 

PC. Uden. Atomic spectral chromatographic detection. In Element Specific Chromatographic Detection by Atomic Emission Spectroscopy, Ed. by PC. Uden, ACS Symposium Series, American Chemical Society, Washington, DC, 1990, in press. PC. Uden, Y. Yoo, T. Wang, and Z. Cheng. Element-selective gas chromatographic detection by atomic plasma emission spectroscopy. Review and developments. J. Chromatogr., 468, 319 (1989). 

Small concentrations of iron can also be deterrnined by flame atomic absorption and inductively coupled plasma emission spectroscopies (see... 

Aluminum is best detected quaUtatively by optical emission spectroscopy. SoHds can be vaporized direcdy in a d-c arc and solutions can be dried on a carbon electrode. Alternatively, aluminum can be detected by plasma emission spectroscopy using an inductively coupled argon plasma or a d-c plasma. Atomic absorption using an aluminum hoUow cathode lamp is also an unambiguous and sensitive quaUtative method for determining alurninum. 

The sodium hydroxide is titrated with HCl. In a thermometric titration (92), the sibcate solution is treated first with hydrochloric acid to measure Na20 and then with hydrofluoric acid to determine precipitated Si02. Lower sibca concentrations are measured with the sibcomolybdate colorimetric method or instmmental techniques. X-ray fluorescence, atomic absorption and plasma emission spectroscopies, ion-selective electrodes, and ion chromatography are utilized to detect principal components as weU as trace cationic and anionic impurities. Eourier transform infrared, ft-nmr, laser Raman, and x-ray... 

An introductory manual that explains the basic concepts of chemistry behind scientific analytical techniques and that reviews their application to archaeology. It explains key terminology, outlines the procedures to be followed in order to produce good data, and describes the function of the basic instrumentation required to carry out those procedures. The manual contains chapters on the basic chemistry and physics necessary to understand the techniques used in analytical chemistry, with more detailed chapters on atomic absorption, inductively coupled plasma emission spectroscopy, neutron activation analysis, X-ray fluorescence, electron microscopy, infrared and Raman spectroscopy, and mass spectrometry. Each chapter describes the operation of the instruments, some hints on the practicalities, and a review of the application of the technique to archaeology, including some case studies. With guides to further reading on the topic, it is an essential tool for practitioners, researchers, and advanced students alike. 

An alternative approach is to analyze the samples using procedures or instrumentation that will give the maximum amount of data for each sample. For example, recent advances in atomic spectroscopy, i.e., inductively coupled argon plasma emission spectroscopy (ICP-AES), allow 20 to 30 elements to be detected simultaneously. 

Li or a Li compound in the flame gives a bright crimson color due to its emission of670.8 nm photons produced by the short-lived species LiOH. This is the property that allows for the spectrophotometric determination of Li by atomic absorption spectroscopy (AAS) down to 20 ppb. Inductively-coupled plasma emission spectroscopy (ICPAES), inductively-coupled plasma mass spectroscopy (ICPMS), and ion chromatography (IC) improve this limit to about 0.1 ppb. A spot test for detection of Li down to 2 ppm is provided by basic KIO4 plus FeCl3. 

Analysis. Mg is quantitatively determined by colorimetry down to 30 ppb, by atomic absorption spectroscopy (AAS) to 10 ppb, and to 0.1 ppb by electrothermal absorption spectroscopy (ETAS), inductively-coupled plasma emission spectroscopy (ICPES), and inductively-coupled plasma mass spectroscopy (ICPMS). A spot test for Mg which extends to 3 ppm is provided by quinalizarin in alcoholic NaOH. If Mg is present the color is bleached by Br2 water. If not. Be is indicated. 

Fruchier rial. (1980), determined by X-ray fluorescence IXRF), except Aland Naby ncuiran activation analysis (NA At. Mg by flame atomic absorption tlidnum borate fusion (FAA), and B by plasma emission spectroscopy (sodium carbonate fusion) (PE5) Saether (1980), determined by XRF after low-temperature ashing (LTA) of raw oil shale samples In = 10). 

The total salt concentration was 0.100 (to.010) N, known to three significant figures. At the high end of the isotherm, the starting solution contained only the ingoing cation at the low end, the solution contained both of the exchanging cations. The equilibrations were carried out for a minimum of three days in a New Brunswick Scientific Company AQUATHERM Water Bath Shaker at 5°, 25°, and 50°C, with temperature control to i0.5°C. Prior to analysis of the equilibrium solutions, the solid and solution phases were rapidly separated by filtration through a Millipore filter immediately after removal from the constant temperature bath. Lead and sodium analyses of the filtrate were obtained by atomic absorption spectroscopy. The cadmium analyses of the filtrate were obtained by plasma emission spectroscopy. These analyses showed that two Na+ ions entered the solution for every Cd2+ or Pb2+ that left ( 2%). 

Atomic absorption and plasma emission spectroscopy are perhaps the most widely used analytical techniques for the determination of silver levels in air, soil, and water. 

Atomic absorption spectrometry with flame (AA-F) or electrothermal atomization furnace (AA-ETA), inductively coupled plasma-emission spectroscopy (ICP-ES), inductively coupled plasma-mass spectrometry (ICP-MS), and high-performance liquid chromatography-mass spectrometry (LC-MS) are state-of-the-art analytical techniques used to measure metals in biological fluids. They are specific and sensitive and provide the cfinical laboratory with the capability to measure a broad array of metals at clinically significant concentrations. For example, ICP-MS is used to measure several metals simultaneously. Photometric assays are also available but require large volumes of sample and have limited analytical performance. Spot tests are also... 

For a detailed discu.ssion of the various plasma sources, see S. J. Hill. Inductively Coupled Plasma Spectrometry and Its Applications. Boca Raton, FL CRC Press, 1999. Inductively Coupled Plasmas in Analytical Atomic Spectroscopy, 2nd ed. A. Montaser and D. W. Golightly. Eds. New York Wiley-VCH Publishers, 1992 Inductively Coupled Plasma Mass Spectrometry. A. Montaser, Ed. New York Wiley, 1998 Inductively Coupled Plasma Emission Spectroscopy. Parts I and 2. P. W. J. M. Bouraans. Ed. New York Wiley. 1987. 

Electrothermal atomizers, which first appeared on the market in about 1970, generally provide enhanced sensitivity because the entire sample is atomized in a short period and the average residence time of the atoms in the optical path is a second ormore. Also, samples are introduced into a confined-volume furnace, which means that they are not diluted nearly as much as they would be in a plasma or flame. Electrothermal atomizers are used for atomic absoiption and atomic fluorescence measurements but have not been applied generally to emission work. They are, however, used to vaporize samples in inductively coupled plasma emission spectroscopy. 

In the past, the most common method of analysis of small anions has been ion-exchange chromatography. For cations, the preferred techniques have been atomic absorption spectroscopy and inductively coupled plasma emission spectroscopy. Recently, however, capillary electrophoretic methods have begun to compete with these traditional methods for small ion analysis. Several major reasons for adoption of electrophoretic methods have been recognized lower equipment costs, smaller sample size requirements, much greater speed, and better resolution. 

---