The mobile phase was water:methanol:tert-methyl
butyl ether (MTBE) (J.T.Baker e Mallinckrodt, EUA) starting at
5:90:5, reaching 0:95:5 in 12 min, 0:89:11 in 25 min, 0:75:25 in
40 min and finally 0:50:50 after a total of 60 min, with a flowrate of
1 mL/min at 33 C