2.4.1 Determination of indican and indoxyl
The qualitative quantification of indican and indoxyl was performed
using high-performance liquid chromatography (HPLC) (UV detector at 280
nm, EX1600, Exformma, USA). An Eclipse XDB C18 column (250 mm × 4.6 mm,
Agilent, USA) was used for separation at a flow rate of 1.0 mL/min and
the temperature of the column oven was 30 ℃. Mobile phase A (deionized
water–acetic acid 100:0.5) and mobile phase B (acetonitrile). The
elution ratio was A-80%: B-20% for 15 min. The UV detection wavelength
was 240 nm.