Fig. 5.

Reconstructed ion chromatograms of the PTO obtained with a SIM, b full scan MS/MS, and c SRM. Column, continuous styrene–divinylbenzene copolymer, 50 × 0.20 mm i.d.; mobile phase, (A) 25 mM CycHDMAA, pH 8.4, 100 μM ascorbic acid, (B) 25 mM CycHDMAA, pH 8.4, 100 % ACN, 100 μM ascorbic acid; linear gradient, 5 % B for 3 min, 5–95 % B in 7 min; flow rate, 2 μl/min; temperature, 70 °C; scan modes, a SIM, b MS/MS, c SRM; sample, PTO, 250 fmol, and (dT)₂₄, 8 pmol