Gradient elution at a flow rate of 1 mL/min
used the following
mobile phases: A, 2.9 g/L sodium dodecyl sulfate in water adjusted
to pH 4.2 with 85% ortho-phosphoric acid;
B, 2.9 g/L sodium
dodecyl sulfate:acetonitrile (62:38, v/v) adjusted to pH 4.2 with
85% ortho-phosphoric acid. The gradient is illustrated in Table