(a) m/z 569.4
(b) m/z 593.5
Figure 4: (a) Chromatograms at m/z 569.4 in a narrower range of retention time for the same pooled M-CSF sample, the plasma sample, and the urine sample processed for F2-IsoPs analysis. The peaks of F2-IsoPs are indicated by asterisks. The concentrations of F2-IsoPs quantified by the routine operation described in Section 2 were 54.9 pg/mL, 13.5 pg/mL, and 851 pg/mL for the CSF sample, the plasma sample, and the urine sample, respectively. (b) Chromatograms for the 5 consecutive injections of the same M-CSF sample (left panel), the same plasma sample (middle panel), and the same urine sample (right panel) processed for F2-IsoPs analysis (Sample-1 to Sample-5) and the 3 subsequent injections of undecane alone (Wash-1 to Wash-3) at m/z 593.5. The chromatograms in the range of 4.4 min to 8.6 min (the end of data acquisition) were compared. The range of retention time corresponding to that for F4-NPs quantification is indicated by the braces although these samples were not used for F4-NPs quantification.