Fig. 2.
Impact of the addition of ascorbic acid a to the mobile phase and b to the sample solvent on the detectability of oligonucleotides. Column, continuous styrene–divinylbenzene copolymer, 50 × 0.20 mm i.d.; mobile phase, a 25 mM CycHDMAA, pH 8.4, 0–570 μM ascorbic acid, b 25 mM CycHDMAA, pH 8.4, 100 % ACN, 0–570 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 mode, MS; sample, PTO, 2 pmol, or (dT)24, 5 pmol, with 0–2.5 mM ascorbic acid