TABLE 5.

Calculated Relative Amounts of Peptides C and C*

Lys Obs (observed) values were calculated from the Lys peak areas on cycles 1, 4, and 12 relative to the Lys standard reported by each facility. Lys Tl (trendline) values refer to expected picomolar amounts of Lys calculated from the trendline equation for peptide B on cycles 1 and 12. Lys (Tl/Obs) is the trendline value divided by the observed value. The average of the Lys 1 and Lys 12 (Tl/Obs) values (Average Tl/Obs) for each facility was used as a correction factor by which Lys (Obs) on cycle 4 (C4 Lys Obs) was multiplied to give a corrected value for the picomolar amount of Lys from peptide C on cycle 4 (C4 Lys Corr). Picomolar amounts of N-ɛ-Acetyl Lys (AcLys) for peptide C* were calculated as described in the text. C*/C Raw refers to the (AcLys)/(C4 Lys Obs) ratio, while C*/C Corr is the (AcLys)/(C4 Lys Corr) ratio.