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. Author manuscript; available in PMC: 2008 Jun 1.
Published in final edited form as: J Am Soc Mass Spectrom. 2007 Feb 22;18(6):997–1006. doi: 10.1016/j.jasms.2007.02.009

Figure 4. LTQ quantitation of tandem mass spectra of Aß from human in vivo labeling with two amino acids.

Figure 4

(a) Tandem MS spectra of Aβ17-28 from human CSF thirteen hours after in vivo13C6-leucine labeling demonstrate unlabeled Aβ17-28 tandem MS ions (top) and labeled Aβ17-28 tandem MS ions (bottom). The leucine containing tandem MS ions demonstrate the additional six Dalton label, as shown by arrows to leucine containing ions.

(b) Tandem MS spectra of Aβ17-28 from human CSF twelve hours after in vivo labeling with 13C6-phenylalanine demonstrate unlabeled ions (top), singly labeled ions (middle) and doubly labeled ions (bottom), as shown by arrows to phenylalanine containing ions.

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