Table 1.

Mobile phase gradient flow program.

Time/min	A/%	B/%
0.00	5	95
3.00	20	80
8.00	25	75
8.10	50	50
10.00	50	50
10.10	5	95
15.00	5	95

A: acetonitrile; B: 10 mM ammonium formate + 0.5% formic acid in Milli-Q water.