Working potential was +950mV (vs. SCE);
fused-silica capillary: 25 m i.d.×75 cm; working electrode: 300 m diameter carbon disk electrode; running buffer: 25 mmol/L SDS in 20 mmol/L
(BB, pH 7.4); separation voltage: 18 kV; injection time: 18 kV/6 s; concentrations
of four analytes, 5.0×10−5 mol/L each.