Comparison atomic spectroscopic methods

Epstein, M. S. "Comparison of Detection Limits In Atomic Spectroscopic Methods of Analysis" - Chapt. 6 in this volume. 

Comparison of Detection Limits in Atomic Spectroscopic Methods of Analysis... 

EAAS and ICP-AES (Ihnat 1984). Klock-enkamper (1997) has a plot of absolute TXRF DLs for residues of aqueous solutions versus element atomic number, under various experimental conditions, and an instructive graphical presentation of actual TXRF detection limits for real samples after specific preparations. Tblgyessy and Klehr (1987) compare detection limits of some analytical methods, including classical methods, AAS, LAS, polarography, mass spectrometry, NAA, and isotope dilution analysis, and include more detailed DL information for NAA techniques. A nice comparison of DLs (in pg) for NAA, ETV-ICP, GF-AAS and ETV-ICP-MS is tabulated by Dybczynski (2001). Naturally, a wealth of information is available in handbooks, an example of which is the one by Robinson (1974) containing detailed listings for various spectroscopic methods. 

The comparison of detection limits Is a fundamental part of many decision-making processes for the analytical chemist. Despite numerous efforts to standardize methodology for the calculation and reporting of detection limits, there is still a wide divergence In the way they appear in the literature. This paper discusses valid and invalid methods to calculate, report, and compare detection limits using atomic spectroscopic techniques. Noises which limit detection are discussed for analytical methods such as plasma emission spectroscopy, atomic absorption spectroscopy and laser excited atomic fluorescence spectroscopy. 

In this review, we focus on the information at an atomic/molecular level that is obtainable via the different techniques. The precise methods and techniques used are not extensively discussed instead we summarize the relevant details and direct the reader toward key references. Nor do we review the potentials that are used in the classical simulations of sorption and diffusion. Derivation and evaluation of these parameters require extensive comparison with detailed spectroscopic data and are beyond the scope of this work. Similarly, the volume of experimental results that may be used in comparison to the calculations is vast. We use representative data taken largely from reviews or books. 

Because the oxirane contains a strained ring consisting only of two carbon atoms and one oxygen atom, a series of theoretical calculations and physical measurements have been performed in order to determine the exact molecular structure. The simplicity of the molecule permits the rather complex quantum-chemical calculations. It follows from the strained nature of the ring that it is a rigid one good comparisons may therefore be made between the geometric data obtained via the various spectroscopic and other physical methods. 

We report on the further physical and chemical characterization of the new forms of molecular carbon, C ) and C70. Our results demonstrate a high yield of production (14%) under optimized conditions and reveal only and C70 in measurable quantity, in an 8S IS ratio. These two new molecular forms of carbon can be completely separated in analytical amounts by column chromatography on alumina. Comparison among mass spectra obtained by the electron impact, laser desorption, and fast atom bombardment (FAB) methods allows a clear assessment of the composition of the mixed and pure samples, and of the fragmentation and double ionization patterns of the molecules. In addition, spectroscopic analyses are reported for the crude mixture by C NMR and by IR spectroscopy in KBr pellet, and for pure C o and C70 in solution by UV-vis spectroscopy. 

---