Table of Contents
ISRN Analytical Chemistry
Volume 2012, Article ID 604389, 11 pages
Research Article

Sol-Gel Thin Films Immobilized with Bromocresol Purple pH-Sensitive Indicator in Presence of Surfactants

1Department of Chemistry, The Islamic University of Gaza, P.O. Box 108, Gaza, Palestine
2Department of Chemistry, Al-Azhar University, P.O. Box 1277, Gaza, Palestine
3Department of Physics, The Islamic University of Gaza, P.O. Box 108, Gaza, Palestine

Received 11 November 2011; Accepted 7 December 2011

Academic Editors: N. Chaniotakis, I. Djerdj, and J. Zieba-Palus

Copyright © 2012 Nizam M. El-Ashgar et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Preparation of transparent sol-gel thin film immobilized with bromocresol purple (BCP) pH-sensitive indicator was made via the acid catalyzed sol-gel reaction of tetraethylorthosilicate and the bromocresol purple indicator (BCP). Different surfactants include cationic cetyl trimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS), and nonionic Triton X-100 (TX-100) were used to improve the mesostructure of the host material and to increase its porosity. The color change behavior of the immobilized bromocresol purple indicator affected significantly in presence of SDS comparing with its free counterpart in aqueous solution. In presence of CTAB and Triton-X 100, the immobilized bromocresol purple indicator shows similar behavior as its free counterpart in aqueous solution. The BCP retains its structure during the sol-gel reactions in terms of response to pH. Different parameters including concentration of indicator and surfactant, temperature, number of layers, response time, life time, and the number of measurements were investigated. The pKa values of the different prepared BCP immobilized thin films were determined. The BCP thin film sensor showed stability, repeatability, reproducibility, fast response, and long life time behavior. The polarized light microscopy indicated that the bromocresol purple indicator molecules are distributed uniformly within the host silica network.