Overlaid chromatograms, monitored at 215 nm, of control urine and control urine spiked with peptide stock solutions to a final concentration of 20 μM

Overlaid chromatograms, monitored at 215 nm, of control urine (solid line) and control urine spiked with peptide stock solutions to a final concentration of 20 μM (dotted line). Urine equivalent to 500 nanomoles creatinine was applied to C-18 reverse phase column and trifluoroacetic acid (TFA) 10 mM and an acetonotril gradient over 115 minutes was run at 1 ml/min. Each peptide was individually dissolved in HPLC-grade water with 0.1% v/v trifluoroacetic acid. The concentration of the individual peptide stock solution was 1mM. CM3-β-casomorphin 1-3 (Y-P-F), CM4-β-casomorphin 1-4 (Y-P-F-P), CM4amid-β-casomorphin 1-4 amide, CM7-β -casomorphin 1-7 (Y-P-F-P-G-P), CM8-β-casomorphin 1-8 (Y-P-F-P-G-P-I), GEC-gluten exorphin C (Y-P-I-S-L), gluten exorphin GEA5-gluten exorphin A5 (G-Y-Y-P-T), GEB5-gluten exorphin B5 (Y-G-G-W-L)