Then, known
amounts of 4 target metal ions were spiked into water samples.
The color of spiked water samples were developed under the
optimum conditions as described in quantitative determinationof metal ions. The semi-quantitative results of naked-eye detection
were compared with the actual metal ions concentrations determined
by ICP. The results in Table 4 show that the actual concentrations
of metal ions are close to naked-eye measurement and are
in the concentration range of the naked-eye detection. Thus, this
method can be applied to determine Cu(II), Pb(II), Fe(III) and Al(III)
in real water samples without any interfering effect.