Figure 2.

Evaluation of matrix effects. A 5 μL injection of 1:20 pooled urine: 0.1% formic acid in water was injected while infusing 1 μg/mL MCPF-Gly (gray) and MCPA-Gly (black). Matrix effects were not observed at the expected elution time (dashed vertical lines) of either analyte (0.93 min for MCPF-Gly and 1.43 min for MCPA-Gly) in the extracted ion chromatogram for the transitions m/z 156.1 → 81.0 and m/z 170.1 → 74.1, respectively.