Interferences polyatomic ion

Principles and Characteristics The major drawbacks of ICP with argon as the support gas lie in numerous isobaric polyatomic ion interferences and in the lack of sufficient energy to ionise halogens and nonmetals to the necessary extent. With these weaknesses of ICP in mind, the possibility of generating microwave-induced plasmas with alternative gases to argon is of interest. 

Main MS interferences Multiply charged ions Argides , dimers Argides , dimers Polyatomic ions... 

Date AR, Ying Y, Stuart ME (1987) The influence of polyatomic ion interferences in analysis by inductively coupled plasma source mass spectrometry (ICP-MS). Spectrochim Acta 42B 3-20... 

However, under certain experimental conditions, not only the dissociation, but also the formation of polyatomic ions with high intensity was observed in the collision cell. For example, 31P+ or 32S+ determination can be performed using oxide ions with high intensity.27 Oxide ions of31P+ or 32S+ which are interference free at m/z = 47 and 48, respectively, are formed with maximum ion intensities in the collision or reaction cell under optimized experimental conditions.27... 

To avoid interferences of isobaric atomic ions of different elements and polyatomic ions at the same nominal mass, off line separation of matrix elements or analyte separation can be applied and/or enrichment and hyphenated techniques such as HPLC- or CE-ICP-MS. Analytical procedures have been developed in the author s laboratory for the determination of spallation nuclides in an irradiated tantalum target using HPLC and CE coupled on line to ICP-MS after dissolution and separation of the tantalum matrix.12,17 The mass spectra of rare earth elements (REEs)... 

Figure 6.8 Interference problem in SIMS polyatomic ion formation by sputtering of borophosphosilicate glass using an 02+ primary ion beam. (R. C. Wilson, F. A. Stevie and C. W. Magee, Secondary Ion Mass Spectrometry (1989). Reproduced by permission of John Wiley Sons, Inc.)...

Chemical separation of matrix and preconcentration of analytes is used to avoid matrix effects, clogging effects on the cones and disturbing interferences of analyte ions with polyatomic ions of matrix elements and plasma gases. A trace/matrix separation method is required for ultratrace analysis. 

Of special interest is the distribution analysis of selenium in certain brain regions. Because the concentration of selenium in brain tissues is relatively low (mostly in the sub-ngg-1 range) and since selenium detection is difficult by LA-ICP-MS due to interference problems by isobaric polyatomic ions, tracer experiments with selenium of natural isotopic pattern were carried out. For example, snails were fed lOOOp-gmF1 selenium solution for 60h. Cross sections lOO/xg... 

In addition, selected rare elements, such as precious metals, were extracted from matrix elements and preconcentrated to avoid isobaric interferences with polyatomic ions as demonstrated for platinum determination in the presence of a relatively high concentration of Hf, resulting in isobaric interferences at m/z = 194, 195 and 196 due to HfO+ diatomic ion formation.17 An improved method for extracting marine sediment fractions and its application for Sr and Nd isotopic analysis is described by Bayon et al.ls... 

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