(A) A 4.0 μL injection of processed pooled plasma in 0.1% formic acid in water was injected onto the C18 column. During injection, a solution of dns-HGA (top, gray, dashed) and dns-MCPG (bottom, black, solid) was infused post-column. No significant plasma matrix effects were observed at the expected retention times of 4.28 ± 0.03 minutes for dns-HGA and 3.88 ± 0.03 minutes for dns-MCPG. (B) For comparison, the same experiment was performed, with 4.0 μL of solvent blank (0.1% formic acid) injected onto the column during the infusion.