Both separations used a Beckman/Altex ultrasphere C₁₈ column, 250 × 4.5 mm with a 50 × 4.5 mm guard column. Mobile phase A was isocratic, 70% methanol with 0.005 M tetrabutylammonium phosphate at a flow rate of 1 ml/min. Mobile phase B used a flow rate of 0.7 ml/min. The elution started with 55% methanol for 1 min, followed by a linear gradient to 86.5% methanol over 30 min, then a gradient to 100% methanol from 45 to 47 min. The column was eluted with 100% methanol for 23 min, then returned over a linear gradient to the starting condition of 55% methanol. For both systems, standard compounds were identified by in-line UV (280 nm) and fluorescence (excitation 375 nm, emission 435 nm) detection.