It should be mentioned that, following this line of reasoning, a

It should be mentioned that, following this line of reasoning, a method

based on comparison of the intensities between cardiolipin M + 1 (i.e., the second) isotopologues, which exploits the uniqueness of doubly-charged cardiolipin ions, has been developed and is very powerful for quantification of individual cardiolipin molecular species [50,57]. The second type of 13C isotope customer reviews correction results from the fact that the monoisotopic peak of the species of interest is isobaric with the second isotopologue of a species that differs from the species of interest with only one more double bond. It is obvious Inhibitors,research,lifescience,medical that this type of correction is not needed if the aforementioned isobaric peaks can be resolved with high mass resolution instrumentation. If the overlapping from the isobaric peaks cannot be resolved (e.g., when low to moderate resolution mass spectrometers are used), corrections on Inhibitors,research,lifescience,medical the apparent monoisotopic peak intensities In′ and Is′ are needed to obtain the actual monoisotopic peak intensities In and Is for the Equation 5. The correction on In′ is derived as follow as an example and the correction

on Is′ can be done similarly. In=In′−IN∗(0.01092n(n−1)/2)=(1−(IN/In′)(0.01092n(n−1)/2))∗In′=Z2∗In′ (7) Where Z2=1−(IN/In′)(0.01092n(n−1)/2) Inhibitors,research,lifescience,medical (8) and is called the type II 13C isotope correction factor; n is the number of total carbon atoms in the species of interest and In′ is the apparent mono-isotopic peak intensity of the species; IN is the mono-isotopic peak intensity of the species that differs from the species of interest with only one more double bond; and In is the corrected monoisotopic peak intensity of the species of interest. This correction factor can Inhibitors,research,lifescience,medical be negligible if IN In′. It should

be specifically pointed out that when a tandem MS spectrum is used for quantification using Equation 5 in which In and Is are obtained after isotope correction using Equation 7 and a similar one, respectively, both types of correction inhibitor Veliparib factors (i.e., Z1 and Z2) may need to be modified because the fragment monitored in tandem MS (i.e., the fragment Inhibitors,research,lifescience,medical ion in PIS or the neutral fragment in NLS) is the monoisotopic one and therefore contains 12C atoms only. Accordingly, the number of total carbon atoms in Equations 6 and 8 should be deduced by subtraction of the number of the carbon atoms in the monitored fragment that contribute no 13C isotopologue Cilengitide effects. It should also be pointed out that if a calibration curve using two or more internal standards covering a wide mass range is used (e.g., in the class-specific tandem MS-based shotgun lipidomics), the first type of correction factor (Z1) can be largely covered by the calibration curve but the second type of correction factor (Z2) should still be considered. In LC-MS based approaches, if the chromatographic separation can totally resolve individual lipid species in a class and a calibration curve is established for each individual species, both correction factors are not needed.

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