Polyatomic ions abundances

There are many different polyatomic anions, including several that are abundant in nature. Each is a stable chemical species that maintains its stmcture in the solid state and in aqueous solution. Polyatomic anions are treated as distinct units when writing chemical formulas, naming compounds, or drawing molecular pictures. The names, formulas, and charges of the more common polyatomic anions are listed in Table 3-4. You should memorize the common polyatomic ions because they appear regularly throughout this textbook. 

Polyatomic Ion Interfered Isotope (Natural Abundance %) Required Resolution... 

Mathematical correction procedures can be used to remove the contribution of a spectral overlap from a measured signal. However, if the signal due to the spectral overlap is much larger than the analyte signal, the signal-to-noise ratio of the corrected signal may be poor. Furthermore, it may not be easy to predict and account for quantitatively all of the potential sources of spectral overlap, particularly those due to polyatomic ions. For isobaric overlaps (Table 3.2), for which the relative isotopic abundances are predictable, mathematical corrections are straightforward. Instrument software often has built-in correction equations for this case. 

The multicomponent spectral fitting approach has been the most successful for a broad range of sample types [ 153,154]. A linear combination of spectra of all of the individual components (elemental ions and polyatomic ions) is optimized for best fit of the experimental spectrum. Model spectra are determined from the natural abundances of the elements and polyatomic model spectra are calculated from the isotopic abundances of the individual element isotopes. Therefore, experimental model spectra are not required. 

For elements with low natural abundance, it can sometimes be found that the isotope ratio measurement limits the LOD. But even for naturally low abundant elements such as uranium, plutonium, and the PGEs, the corresponding isotope intensities are often subject to interferences by small contributions from polyatomic ions [25, 26]. Such interferences simulate an additional blank value, which is still covered by the blank measurement, at least if the corresponding procedure with the blank solution gives rise to the same polyatomic ions as the real sample. 

How sensitive are calculated abundances to dissociative recombination branching ratios In order to answer this question, Millar et al. (1987) have attempted to use the Bates approach to estimate branching ratios for a wide variety of polyatomic ions, to incorporate the results into a pseudo-time-dependent model of dense clouds, and to... 

In contrast, for polyatomic molecules, fragment ion abundances are usually much smaller if the ionization and subsequent fragmentation occur within a cluster. For instance, for a propane cluster, the relative abundance of the parent molecular ion C3Hg and the abundances of the first-generation fragment ions C3H, C3H, C2FI... 

Ketterer, M. E., and Biddle, D.A. (1992). Multivariate calibration in inductively coupled plasma mass spectrometry. 2. Effect of changes in abundances of interfering polyatomic ions. Anal. Chem. 64(17), 1819. 

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