After flow reversal, the sample zone was transported to the electrochemical FC at the required flow rate (2–20 μL/s).
During the contact time between the sample and the working electrode, the analyte accumulated onto the electrode surface at an open circuit.
After accumulation step, 0.1 M PBS was propelled through the FC.
A stripping voltammogram was recorded under the stopped-flow conditions in the anodic potential range from 0.2 V to 1.4 V.
The resulting stripping peak current of purine nucleobases was measured.
Before the beginning of a new sample pre-treatment step, for removing adsorbed compounds, the electrode surface was regenerated by scanning potential (number of scans = 5) in the blank PBS for about 7 cycles.
HClO4 was used to on-line activate the electrode surface, when necessary.