Sequential Determination of Total Arsenic and Cadmium in Concentrated Cadmium Sulphate Solutions by Flow-Through Stripping Chronopotentiometry after Online Cation Exchanger Separation

Table 2

Timetable of the separation unit and the measurement sequence.

Step	Action	Note
1	Filling the sampling loop with sample or standard, the excess is directed to the waste though the valve No. 4. Duration 90 s
2	Pumping the sample/standard from the sampling loop through the column to the reservoir. Duration 90 s
3	A ready signal is sent to start the uptake of the sample by the analytical unit. The content of the reservoir is taken to the analytical unit and arsenic is measured	Arsenic measurement
4	The column is rinsed with the regeneration solution which elutes cadmium. The eluted solution is directed to the waste. Duration 110 s
5	A zone of the eluted solution is diverted to the reservoir through the valve No. 5 (duration 20 s)
6	A ready signal is sent to start the uptake by the analytical unit. The content of the reservoir is taken to the analytical unit and cadmium is measured	Cadmium measurement
7	In the meantime the column is rinsed with the regeneration solution and the solution is lead to the waste through the valve No. 5. Duration 150 s
8	The column is rinsed with water. Duration 180 s
9	The SPU is set to standby and is waiting for the next start