Loading curve and reproducibility. (A, B) Protein and precursor ion identifications, respectively, at each DBS sample load with identifications in individual replicates marked by black circles. The colors represent %CV criteria: blue < 10%; orange 10–20%; gray 20–30%; and green > 30%. (C, D) Protein and precursor ion reproducibility on 3 different days (10 replicate injections) and interday reproducibility. The same color code is repeated from Panels A and B, except in D: green 30–40% (green) and pale green > 40%.