Figure 1: Schematic of the change-over valves in the ion chromatograph. Valve 1 is the part of the standard setup; Valve 2 and the associated small clean-up column were added for chloride removal. (a) Valve 1 during normal operation without the chloride removal step. The tube going to the column, suppressor, and conductivity detector can optionally also extend further to transfer the sample into the ICP-MS. (b) Valve 2 in stand-by mode when chloride removal is not needed. Here the small column is constantly flushed with water to keep it hydrated. (c) Valve 1 in chloride removal mode. NaOH is introduced by an additional pump. (d) Valve 2 in chloride removal mode, receiving solution from Valve 1, when Valve 1 is in the ‘inject’ position. Valve 2 is in the ‘load’ position while receiving sample from Valve 1 and switches to ‘inject’ after 2.5 minutes.