Mass discrimination effects

Mason TFD, Weiss DJ, Horstwood M, Parrish RR, Russell SS, Mullane E, Coles BJ (2004b) High-precision Cu and Zn isotope analysis by plasma source mass spectrometry. Part 2. Correcting for mass discrimination effects. J Anal At Spectrom 19 218-226... 

Figure 8.2 Mass discrimination effect in ICP-MS. (].S. Becker,]. Anal. At. Spectrom., 17, 1172 (2002). Reproduced by permission of The Royal Society of Chemistry.)...

The instrumental mass discrimination effects between MC-ICP-MS (VG Axiom and Isoprobe from Micromass) and MC-TIMS (VG Sector 54, Micromass) were compared for 8UB measurements.82 Measurements by MC-ICP-MS yielded more precise isotope ratios than those obtained by TIMS (one magnitude better compared to negative ion TIMS) despite showing the highest mass bias. However, the mass discrimination effects appear to be unaffected for 8nB values.82... 

Hirata, T. (1996) Lead isotopic analyses of NIST standard reference materials using multiple collector inductively coupled plasma mass spectrometry with a modified external correction method for mass discrimination effect. Analyst 121, 1407-1411. 

Solutions exist to deal with many of the mass discrimination effects of TIMS Except for those elements that participate heavily In natural physlco- chemical reactions such as 0 and S, and those... 

Since these mass discrimination effects are largely a function of the vaporization process the same discrimination and correction techniques would be applicable to the resonance ionization processes that utilize thermal vapor sources ... 

In addition to structural characterization, quantitative analysis of the various species is important in many application areas. Due to the effect of unsaturation on the relative abundance of the [M+H]" and mass discrimination effects in favour of the DAG fragment ion in a quadrupole mass analyser, determination of response factors for the various species is required for an accurate quantitative analysis [24]. Therefore, limiting the number of standards that are required in the analysis of complex TAG mixtures is an important topic in quantitation. From a comparison of four different approaches, Byrdwell et al. [24] concluded that the most accurate method involved the calculation of response factors from contributions from individual fatty acids to the TAG response. This approach was apphed with good results by others as well [17]. 

When electron impact sources are employed, some mass discrimination effects can be attributed to space charges which build up in the ionization chamber. The magnitude of these effects may be determined by measuring the isotope ratio as a function of the ionizing current and then extrapolating to zero current. In addition, isotope effects may occur in the dissociation... 

In 1950, Nier (86) reported the redetermination of the relative abundances of the isotopes of a number of elements with an accuracy of 0.1%. The mass spectrometer used in these studies was calibrated for mass discrimination effects by means of carefully prepared synthetic mixtures of A36 and A40. Samples of elements for which accurate isotope ratios are... 

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