Basic mobile phases utilized 5 mM piperidine in water (mobile phase A) and acetonitrile (mobile phase B) on a Dionex Ultimate 3000. Desalting methods employed an isocratic gradient of 80%B. Six-port valve switches were programmed based on column length to load sample, elute desalted oligonucleotides, and divert salts (Figure ). Columns were packed in-house with Waters Xbridge Phenyl (3.5 µm, 130 Å) pH-resistant stationary phase to 5 cm in 100 µm ID fused silica with a homemade Kasil frit. During analysis, the loading pump flow rate was 1 µL/min, while the flow rate of the analytical pump was decreased to 0.3 µL/min during elution of the desalted oligonucleotide and was otherwise held at 1.0 µL/min.