Before commencing the leaching procedure, the spiral PTFE
column was filled with water, after which the solid sample (50 mg)
was introduced into the column (in the stationary mode) as a
suspension in 5 mL in de-ionized water. Then, extra 5 mL of deionized water were added into the sample test-tube and injected
into the column. Then, while the column was rotated (the rotation
and revolution speeds were 800 rpm), de-ionized water used as the
mobile phase (eluent) was continuously fed to the column inlet
(0.5 mL/min). The solid sample was retained inside the rotating
column as the stationary phase under the action of centrifugal force
field throughout the experiment. The collected sub-fractions of
effluent (5 mL each) after filtration were directly analysed by ICPMS. After the leaching procedure has been finished, the residue of
the solid sample was removed from the stopped column by
pumping water at a flow rate of 30 mL/min