After digestion, the assay of Na and K levels was performed by atomic absorption spectrophotometer 240FS AA (Agilent Technologies, USA) (Szymczycha-Madeja et al., 2014 , Villagrán et al., 2004 (link)). After flame atomization, K and Na absorbed the resonance lines of 766 nm and 589 nm respectively.
The level of chloride and citrate was determined by DIONEX AQUION (Thermo Fisher Scientific, America) which is equipped with the AS11-HC guard column (4 × 50 mm, 4 μm) and AS11-HC analytical column (4 × 250 mm, 4 μm). 25 μL sample was injected and the suppression current was 50 mA. 20 mM KOH solution was used as the eluent at a flow rate of 1 mL/minute for 13 min (Penniston et al., 2008 (link)).
The level of chloride and citrate was determined by DIONEX AQUION (Thermo Fisher Scientific, America) which is equipped with the AS11-HC guard column (4 × 50 mm, 4 μm) and AS11-HC analytical column (4 × 250 mm, 4 μm). 25 μL sample was injected and the suppression current was 50 mA. 20 mM KOH solution was used as the eluent at a flow rate of 1 mL/minute for 13 min (Penniston et al., 2008 (link)).