was examined under the optimum conditions (pH, eluent, etc.) by
passing 10 mL of sample solution through the microcolumn. The
flow rates were adjusted in the range of 0.5–3.5 mL min−1 controlled
by a peristaltic pump. The results are shown in Fig. 4. It
was found that the retention of the studied ion was practically not
changed up to 2.0 mL min−1 flow rate. The recovery of the analyte
decreased slightly when the flow rate was over 2.0 mL min−1. Thus,
a flow rate of 2.0 mL min−1 was selected throughout the column
experiment.