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Laser mass bias

The main challenge of LA-ICP-MS analyses for U-Pb geochronological purposes is to constrain mass bias within the ICP-MS (see also Chapter 5) and elemental fractionation during laser ablation (see also Chapter 4), while simultaneously obtaining the maximum spatial resolution to resolve different age zones, as illustrated in Figure 9.3, and an adequate signal intensity to obtain the desired precision on the analysis. These are demands that unfortunately conflict with each other, so a compromise has to be found. [Pg.245]

The complexity of some of these problems of interference, matrix and inter-element fractionation is exemplified by the analysis of Sr isotopes in both solution mode and laser ablation (LA-) MC-ICP-MS. Sr isotope studies have been traditionally carried out using TIMS although MC-ICP-MS can also be used but requires correction (or monitoring) for mass bias, interfering elements, doubly charged ions, argides and dimers, and unidentified interferences. Primarily, isobaric interferences from Rb and Kr (present in trace quantities within the Ar plasma gas) must be corrected but this is not wholly straightforward. [Pg.63]

Since these early studies, efforts have concentrated on expanding the number of isotope systems to which LA-MC-ICP-MS can be applied, and mechanisms to correct for inter-element interference, mass bias and laser-induced isotopic fractionation. Where possible, internal normalisation of data using fractionation factors determined from a pair of stable isotopes of the element under investigation is the preferred route of data correction. Where this is not possible, external normalisation using another element at similar mass is used but, especially at light masses, this approach may not readily correct for laser-induced preferential volatilisation of lighter isotopes which may vary on an element-by-element basis. ... [Pg.442]

O. Vorm and P. Roepstorff. Detector Bias Gating for Improved Detector Response and Calibration in Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry. J. Mass Spectrom., 31(1996) 351-356. [Pg.86]


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See also in sourсe #XX -- [ Pg.114 , Pg.115 ]




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