The mass bias was corrected with a certified reference material (Common Lead Isotopic Standard, SRM 981, NIST) using the standard bracketing technique described in [ 28].
The standard isotopic 48-h H-hypoxanthine-based test (21 ) was used, with minor modifications, to assess the sensitivity of F32-ART5 and F32-TEM lines to 10 antimalarial drugs (9, 20 ).
Moreover, the deviations were possibly derived from the worse accuracy for the excessively D-enriched ( {updelta mathrm{D}}_{{mathrm{H}}_2mathrm{O}} ) measurement resulting from the over range of calibration by using the commercial standards having relatively lower isotopic values (see Methods) than the ( {updelta mathrm{D}}_{{mathrm{H}}_2mathrm{O}} ) values of the experimental batches (Table 2).
However, the lack of steady state in critically ill patients and the time taken for equilibration preclude the simultaneous use of gold standard isotopic tracers as a formal validating technique.
Using the quantification toolbox, the isotopic ratios for all identified proteins were determined as weighted average of the isotopic ratios of the corresponding light over heavy peptides.
We optimized the method of identification of lysine residues prone to glycation using the combination of LC-MS, isotopic labeling, and modified synthetic peptide standards with the glycated lysine derivative (Fmoc-Lys i, i-Fmoc-Lys iH).
Isotopic fractionation can be modeled as a Rayleigh process using the following equation: where δ is the isotopic composition of the product, p, in per mil, δo is the initial isotopic composition of the substrate (reactant), s, in per mil, εp-s is the isotopic enrichment factor, in per mil, and f is the remaining fraction of the substrate, unit less.
Reliable 87Sr/86Sr ratios of the spike-standard mixed solutions were obtained using the new mass bias factor calculated on the basis of measured Sr isotopic ratios.
Sm isotopic compositions were iteratively solved to minimize the residual sum of squares between corrected 143Nd/144Nd ratio of Sm-doped Nd standard solution and the unspiked value using the Excel Solver.
Oxygen isotopic analysis was carried out using the automated H2O CO2 equilibrium method (Epstein and Mayeda 1953).
