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. Author manuscript; available in PMC: 2022 Jun 16.
Published in final edited form as: J Chromatogr A. 2021 May 28;1651:462294. doi: 10.1016/j.chroma.2021.462294

Fig. 4.

Fig. 4.

Chromatograms (a–d) showing the effect of pH in the small increment (9.25–10.0) for the separation of six KP metabolites. The plots shown in (e-g) represent average efficiency (Navg), signal-to-noise (S/N) ratio and resolution (Rs) of six KP metabolites. The mobile phase, 15 mmol/L (NH4)2CO3, was adjusted to various pH values using 14.5 M NH4OH. Peak identifications: 1. TRP (16.25 μM), 2. KYN (33.75 μM), 3. HKYN (68.5 μM), 4. KA (15 μM), 5. AA (15 μM), 6. XA (33.75 μM). Other CEC-ESI-MS conditions are the same as described in Fig. 3.