Behavior of α-Naphtholphthalein as Analytical pH-Indicator Entrapped into Sol Gel Matrix.

This study considers the nature of interactions between the sol gel derived inorganic matrix and α-naphtholphthalein pH-indicator, the method is based on the physical entrapment of the indicator molecules in sol gel matrix, the immobilized α-naphtholphthalein pH-indicator shows similar behavior as its solution counterpart. The UV/VIS spectra indicate that the α-naphtholphthalein retains its structure during the sol gel reactions in terms of response to pH. α-Naphtholphthalein can be regarded as uniformly distributed in the sol gel matrix. This observation has been confirmed using polarized microscopy. [ABSTRACT FROM AUTHOR]