Atomic spectroscopy, laboratory

The atomic spectroscopist is typically involved in supporting a new potential drug candidate before the final salt and/or crystal form have been selected. Several forms of the drug substance (salt forms, and/or polymorphs) are considered during the discovery phase and are generated in small laboratory batches via several synthetic pathways or crystallization procedures. The atomic spectroscopy laboratory plays an important role in the selection of the final form by assaying these samples for trace metals, salt counter-ions and trace catalysts used in the syntheses. Once a final form has been selected, testing continues to support the optimization of the synthetic process. 

The role that the atomic spectroscopy laboratory plays in the drug development process is an important one. It helps ensures the safety and quality of the drug products that are approved by the FDA. 

G. Schlemmer and B. Radziuk, A Laboratory Guide to Graphite Furnace Analytical Atomic Spectroscopy, Springer-Verlag, Berlin (1998). 

Figure 21-6 An electrically heated graphite furnace for atomic spectroscopy (—38 mm long, in this case). [Courtesy Instrumentation Laboratory, Wiirrington, MA.]...

The dialogue between users and providers of atomic data is a two-way conversation, with atomic physicists beginning to view astrophysical and laboratory plasmas as unique sources of new information about the structure of complex atomic species. A number of monographs on theoretical atomic spectroscopy cowritten by theoreticians and astrophysicists and dedicated to astrophysicists also contribute to better mutual understanding [18, 320]. 

However, as real-world analytical problems are most often neither ideal nor routine, analytical instrumentation supplemental to atomic spectroscopy would be a great advantage in developing methods for non routine applications. Thus, it is becoming apparent that the well-equipped analytical laboratory of the future will incorporate both atomic spectroscopy and ion chromatography. 

The fact that excited atoms give off specific colors and not a rainbow of colors suggested to Niels Bohr, a Danish physicist, that electrons are permitted in only certain locations within the atom. These locations are called energy levels. Each element behaves in its own unique way when excited by heat or electricity and produces a very specific pattern of lines of color called the atomic spectrum of that element (Figure 8.5). This unique chemical fingerprint is the foundation of atomic spectroscopy, a method of analysis used by forensic and medical laboratories to identify elements... 

In terms of the sample, specificity of the method is difficult to establish. It may be that the clean up procedure allows the final sample to be analysed free of interferences, but the process of obtaining such a laboratory sample from the original material in the environment has a great number of uncontrollable variables. Obvious interferents may be known and procedures adopted to avoid them. An example is the presence of high levels of sodium chloride in sea water samples, which proves difficult for atomic spectroscopy methods. 

An absolute method is based on stoichiometric chemical reactions such as titrations (acid/base, redox, precipitation and chelometry, coulometry, voltammetry). Methods that are accepted or developed by official laboratories are usually accurate, precise and used by other laboratories throughout the world. A significant number of methods for atomic spectroscopy also fall into these categories and are readily available from the appropriate literature. Developed and accepted methods give confidence in reporting of results because all the teething problems and pitfalls associated with that method would have been observed and noted by other users. Standards must be as close as possible to the... 

In the last 20 years atomic spectroscopy has made great strides, particularly with the introduction of new improved optic designs and detection methods. These improvements have led to superior resolution of the wavelengths of the excited atoms and detection techniques measuring lower levels of metals with ease. After a slow and problematic start, inductively coupled plasma optical emission spectrometry (ICP-OES) has become an established technique in most laboratories analysing a wide range of sample matrices reporting accurate and precise results. 

ICP-OES continues to dominate the market because of its ease of use and relatively low maintenance cost. Inductively coupled plasma mass spectrometry (ICP-MS) is a very powerful state-of-the-art technique used for metal analysis of all kinds of samples but requires highly skilled operators. A vast amount of information is received that is not necessarily required as part of problem-solving or routine support. The cost difference and relative freedom from maintenance problems would favour ICP-OES. This book is aimed at practitioners requiring multi-elemental analysis in industrial, environmental, pharmaceutical and research laboratories, where information on identification and quantification is required on a regular basis. The main focus of this book will be on sample preparation, a topic overlooked in most books on atomic spectroscopy. It is aimed at most ICP-OES and ICP-MS users to show that the instrument is useless unless the sample is prepared in a suitable state that can be used to accurately and precisely quantify the metals present. 

Burners Sources of heat for laboratory operations or for flame atomic spectroscopy. 

We have acquired a contract from a company called The Solution Makers located in northern New Jersey. This company prepares and sells certified standard solutions for use in accredited laboratories worldwide. They are especially known for their high-quality atomic absorption standard solutions widely used to calibrate atomic spectroscopy instruments as well as other instruments. The chemicals they use to prepare these solutions are purchased from The Inorganic Chemical Company of North America (ICCNA). 

Applications considerations are included in many chapters in Vol 3 of Dean and Rains (1975) devoted to the determination of specific elements, and in various natural and manufactured materials. Methods for analytical atomic spectroscopy, 8th edition (ASTM 1987) contains a wealth of information based on evaluation and approval deliberations by the respected ASTM, including various computation practices, general laboratory practices, practices and methods for analysis of metallurgical and inorganic materials by spectrochemical techniques including flame atomic emission. Dawson et al. (1993) have published a tutorial review on background and background correction in analytical atomic emission spectrometry. 

The spectroscopic techniques most commonly used for process analysis involve the use of infrared or UV/visible radiation. Mass spectroscopy has a considerable number of varied apphcations especially in the area of gas analysis. NMR technology is being increasingly used for a range of apphcations. Atomic spectroscopies, used extensively from a laboratory base for process control, are finding apphcations in automatic on-line measurement where the sampling systems can be suitably... 

To conclude our discussion on GFAA, as we did for ICP-AES, a calibration plot for the element Cr (as total chromium) is presented in Fig. 4.80 and is taken from the author s laboratory using the Model 310 (Perkin-Elmer) GFAA spectrophotometer. We also close our atomic spectroscopy discussion by summarizing in Table 4.21 the three major techniques to measure trace levels of metals from environmental samples and how to handle interferences. We now turn to two remaining determinative techniques of relevance to TEQA, infrared absorption spectroscopy, and capillary electrophoresis. 

As mentioned in the introduction to this chapter, visible/UV Fourier transform instruments are still found mainly as unique, one-of-a-kind instruments in a few spectroscopy laboratories. The research topics being pursued with these Fourier transform instruments include atomic spectrochemical measurements, atomic and molecular emission spectroscopy from hollow cathode discharges, and molecular absorption spectroscopy for accurate frequency standards and molecular constants. In each of these research efforts, the Fourier transform method has proven useful. In part, the success of this method is derived from the fundamental advantage originally stated by Jacquinot, and to some extend from the advantage stated by Fellgett. 

Atomic spectroscopy is a principal tool for measuring metallic elements at major and trace levels in industrial and environmental laboratories. With an autosampler to feed in new samples automatically, each instrument can turn out hundreds of analyses per day. 

Gutmacher, R. G. (1964) Atomic Spectroscopy of Berkelium (Abstract), US Atomic Energy Commission Document UCRL-12275-T, University of California Lawrence Livermore Radiation Laboratory. 

Lewen N, Schenkenberger M, Raglione T and Mathew S (1997) The application of several atomic spectroscopy techniques in a pharmaceutical analytical research and development laboratory. Spectroscopy 12 14-23. 

See also Food and Dairy Products, Applications of Atomic Spectroscopy Food Science, Applications of Mass Spectrometry Food Science, Applications of NMR Spectroscopy Laboratory Information Management Systems (LIMS) Pharmaceutical Applications of Atomic Spectroscopy. 

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