Table 1. HPLC conditions of compounds.

Compound (LogP)	solvent A of mobile phase	solvent B of mobile phase	Flow (μL/min)	Column	Mobile-phase gradient
Ceftazidime (0.4)	5 mM ammonium formate in water	acetonitrile	300	Shiseido CAPCELL PAK C18 MG S5 (2.0 mmi.d.×150 mm)	0–4 min 90%A, 4.1–7 min 10%A, 7.1–13 min 90%A
Minocycline (-0.6)	5 mM ammonium formate in water	acetonitrile	300	Shiseido CAPCELL PAK C18 MG S5 (2.0 mmi.d.×150 mm)	0–4 min 90%A, 4.1–6 min 20%A, 6.1–11 min 90%A
Cefotaxime (-1.4)	5 mM ammonium formate in water	acetonitrile	300	Shiseido CAPCELL PAK C18 MG S5 (2.0 mmi.d.×150 mm)	0–4 min 90%A, 4.1–6 min 20%A, 6.1–10 min 90%A
Netilmicin (-4.3)	0.1%TFA in water	acetonitrile	200	Shiseido CAPCELL PAK ST (2.0 mmi.d.×150 mm)	0–4 min 85%A, 4.1–6 min 20%A, 6.1–10 min 85%A