The absorption spectra of dithizone in solution of
methanol/water and immobilized forms at pH 2 on hydrolyzed
cellulose acetate are shown in Fig. 1. The spectral
change is a result of addition of Hg2+ ions and complex
formation. The spectral characteristic of this sensor
showed two maxima at 610 and 483 nm. It is important
to note that the absorption spectra of immobilized indicator
is red shifted in comparison to those of their soluble
form (610 instead of 589 nm). This can suggest that
the structured conformation of the immobilized indicators
is more planar than that of its soluble analogue [21].
The wavelength of 610 nm was selected for further studies
because of higher selectivity and sensitivity at this
wavelength.