Figure 8.
Separation of peptide mixture using a tandem system consisting of 10 cm × 100 μm I.D. monolithic column containing GNPs and 15 cm × 75 μm I.D. C18 packed column. Conditions: concentration of each peptide in solution 0.1 mg/mL, injection volume 100 nL, flow rate, 0.5 μL/min, mobile phases, step 1: aqueous 0.1% (v/v) formic acid; step 2: A, aqueous 0.1% (v/v) formic acid; B, 0.1% (v/v) formic acid in acetonitrile, gradient 0-60 % B in A in 8 min; step 3: 2.0 mol/L aqueous 2-mercaptoethanol; step 4: A, aqueous 0.1% (v/v) formic acid; B, 0.1% (v/v) formic acid in acetonitrile, gradient 0-60 % B in A in 8 min, UV detection at 214 nm. For peak assignment see Figure 7.