Chromatographic separation of the analytes was achieved on a Phenomenex Synergi Polar-RP column (7.5 cm × 0.2 cm, 4 µm held at 40°C) using the following gradient: 85%B for 0.5 min, %B increased to 99% in 3 min and held at 99% for an additional 2 min. The column was re-equilibrated at initial conditions for 3 min before each injection. The flow rate was 0.5 ml/min. Component A was water and B was methanol and each component contained 80 µM silver acetate and 0.5% acetic acid (v:v).
