Multiple species-specific spiking

P. Rodriguez-Gonzalez, M. Monperrus, J. I. Garcia Alonso, D. Amouroux and O. F. X. Donard, Comparison of different numerical approaches for multiple spiking species-specific isotope dilution analysis exemplified by the determination of butyltin species in sediments, J. Anal. At. Spectrom., 22, 2007, 1373-1382. 

Metabolite quantitation in humans and two species of preclinical animals at Cmax in plasma is shown in Figure 16.11. UPLC—AMS separated and quantified fractions of variable width that depended on metabolites expected from the animal species. UV absorbance (dashed lines in the figure) monitored resolution and provided a marker near 8 min for one metabolite spiked into the plasma samples before separation. AMS data is plotted as the fraction of the total eluted isotope signal in the trace on both linear and log scales for 18 compounds that produced peaks in one or more of the three species. Multiple metabolic differences are noted not only between the human and the animals but also between the two animal species. Specifically, the metabolites included as a spike, M , is disproportionately found in humans at more than 10% of the total content and only minimally, but distinctly, in species 2. Chromatographic conditions broadened the UV metabolite peak in species 1 with resolution also lost in leaving only a hint of the metabolite presence. M is the only other metabolite exceeding 10% of total in human plasma in this... 

Speciation Analysis Simultaneous Determination of Multiple Species of the Same Element At the beginning of the development of species-specific isotope dilution, only a single spike compound was used [77]. Later, species-spedfic IGP-IDMS has also been used for the determination of more than one spedes of the same element, using different spike spedes labeled with the same isotope. Examples include the determination of mono- and dimethylmercury (MMM and DMM) and of the three butyltin compounds TBT, DBT, and MBT [80-83]. Various spike isotopes, usually of medium natural abundance, such as Hg or ° Hg and Sn, Sn, or Sn, have been applied. The reason for selecting this type of spike... 

An important improvement in the calculation procedure for species-specific multiple spiking was obtained by introducing isotope pattern deconvolution (IPD). The difference from the conventional multiple-spiking technique is the use of isotopic abundances instead of isotope ratios for calculation. The measurement of additional isotopes not used for calculation of interconversion reactions provides internal correction for mass bias effects without the application of an external isotopic standard, but also correction for spectral interferences. The basic equations applied in IPD can be found in the literature [78], This new method is predominantly applied in speciation analysis, but also in metabolism studies using stable isotopes [97, 98]. For quantification of elemental species, including... 

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