Jul 10, 2020 · After the filtration of the eluate using a filter RephiQuik PTFE (0.45 μm, RephiLe Bioscience Ltd., Shanghai, China), the solution was analyzed by HPLC at isocratic conditions using 25 mM phosphate buffer plus 1% (v/v) methanol at pH = 2.4 (gradient of purity 99.9% with HPLC grade) as a mobile phase (flow rate, 1 mL/min; loop, 200 μL) with