Figure 5 Comparison of chromatograms for different volume injections but constant mass (800 amol) of met-enkephalin (peak indicated by arrow). Injections were 10 nL of 80 nM (A), 100 nL of 8.0 nM (B), and 1000 nL of 0.80 nM (C). Capillary column was 8 cm long, 25 µm i.d. fused silica capillary packed with 5 µm Alltima C-18 reversed-phase particles. After loading sample, the column was rinsed with 5% solvent B-95% solvent A for 5 min before gradient elution started. Gradient elution started at 5% solvent B, linearly changed to 50% solvent B in 5 min, kept at this composition for 2 min, and then stepped back to 5% solvent B. Solvent A was 1 mM phosphate buffer in 10 mM sodium sulfate adjusted to pH 7.0. Solvent B was 40% (v/v) of solvent A with 60% acetonitrile. Detection utilized a 9 µm diameter by 2 mm long C-fiber electrode inserted into the outlet of the column. Detector electrode potential

DOI link for Figure 5 Comparison of chromatograms for different volume injections but constant mass (800 amol) of met-enkephalin (peak indicated by arrow). Injections were 10 nL of 80 nM (A), 100 nL of 8.0 nM (B), and 1000 nL of 0.80 nM (C). Capillary column was 8 cm long, 25 µm i.d. fused silica capillary packed with 5 µm Alltima C-18 reversed-phase particles. After loading sample, the column was rinsed with 5% solvent B-95% solvent A for 5 min before gradient elution started. Gradient elution started at 5% solvent B, linearly changed to 50% solvent B in 5 min, kept at this composition for 2 min, and then stepped back to 5% solvent B. Solvent A was 1 mM phosphate buffer in 10 mM sodium sulfate adjusted to pH 7.0. Solvent B was 40% (v/v) of solvent A with 60% acetonitrile. Detection utilized a 9 µm diameter by 2 mm long C-fiber electrode inserted into the outlet of the column. Detector electrode potential

Figure 5 Comparison of chromatograms for different volume injections but constant mass (800 amol) of met-enkephalin (peak indicated by arrow). Injections were 10 nL of 80 nM (A), 100 nL of 8.0 nM (B), and 1000 nL of 0.80 nM (C). Capillary column was 8 cm long, 25 µm i.d. fused silica capillary packed with 5 µm Alltima C-18 reversed-phase particles. After loading sample, the column was rinsed with 5% solvent B-95% solvent A for 5 min before gradient elution started. Gradient elution started at 5% solvent B, linearly changed to 50% solvent B in 5 min, kept at this composition for 2 min, and then stepped back to 5% solvent B. Solvent A was 1 mM phosphate buffer in 10 mM sodium sulfate adjusted to pH 7.0. Solvent B was 40% (v/v) of solvent A with 60% acetonitrile. Detection utilized a 9 µm diameter by 2 mm long C-fiber electrode inserted into the outlet of the column. Detector electrode potential