Retention of interferent ions on the PUF minicolumn
is dependent on pH as thiocyanate complex
formation is affected by this parameter. This effect
on the separation was studied in a pH range 0.5±6.0
(adjustments were made with nitric acid) with solutions
containing Ni(II) 1 mg/ml, Fe(III), Cu(II) and
Zn(II) 50 mg/ml each one. It was observed that signals
were always constants for pH below 3.0. For pH over
3.0 signals increase, showing that concomitants
passed through the PUF minicolumn, giving rise to
interferences.