BThe mobile phase was a binary mixture of A: ACN–MeOH–citricacid (21.9 mM, adjusted to pH 4.7 using concentrated ammonia)30:10:60 v/v/v solution and B: ACN–MeOH–citric acid solu-tion (21.9 mM, adjusted to pH 3.9 using concentrated ammonia)68:12:20 v/v/v in a gradient elution mode with the following pro-gram: 0–10 min: 0% B, 10–20 min: 30% B, 20–40 min: 100% B.