Background: Nitrite is a carcinogenic compound and can be found in water, soil, and food
products. Determining the presence of nitrite has become very important in monitoring water quality and
Methods: A highly sensitive optical chemical sensor based on sol-gel film for trace amounts of nitrite was
developed. The Xylene cyanol FF dye doped organic-inorganic silica hybrid film was obtained by copolymerization
of tetraethoxysilane (TEOS) with methyltriethoxysilane (MTEOS) as an organically
modied sol-gel precursor, and deposited onto glass substrates using spin-coating techniques.
Results: The organically modified silicate thin film prepared with a 2:1 TEOS: MTEOS volume ratio was
found to be the best in terms of transparency, uniformity, and stability. The organically modified silicate
thin film changes from blue to yellow when added to a nitrite aqueous solution, causing decreased absorbance
of the film at 618 nm. The experimental results show that the film has a good linear response (R2 =
0.9833) to nitrite in the range of 10 to 0.1 µg. L1.
Conclusion: The XCFF dye doped sol-gel film has high sensitivity, selectivity for nitrite in the water
samples. The detection limit of film for nitrite was found to be 0.011 µg. L1 (0.24 nmol.L-1). This sol-gel
film is stable, inexpensive, and easily fabricated. It could be practical used for the determination of nitrite
in most real water samples.