Dual-analyte spectroscopic sensing in sol-gel derived polyelectrolyte-silica composite thin films

Area of Science:

• Materials Science
• Analytical Chemistry
• Spectroscopy

Background:

• Developing sensitive and selective methods for detecting metal ions and pH is crucial for environmental analysis.
• Immobilizing indicator molecules in solid matrices offers advantages over traditional solution-based methods, including reusability and simplified handling.
• Sol-gel derived composite films provide a versatile platform for sensor development due to their tunable properties and high surface area.

Purpose of the Study:

• To immobilize Ferrozine (iron indicator) and HPTS (pH indicator) within poly(dimethyldiallylammonium chloride)-silica (PDMDAAC-SiO(2)) composite thin films.
• To investigate the spectroscopic response of the immobilized indicators to Fe(2+) and H(+) using attenuated total reflection (ATR) spectrometry.
• To characterize the performance of the developed sensor films in terms of linear range and sensitivity for both analytes.

Main Methods:

• Ion-exchange immobilization of Ferrozine and HPTS onto PDMDAAC-SiO(2) composite thin films on glass optical substrates.
• Attenuated Total Reflection (ATR) spectrometry was employed for spectroscopic analysis.
• Measurements were conducted at specific wavelengths: 562 nm for Fe(2+) and 460 nm for H(+) detection.

Main Results:

• The Ferrozine/HPTS immobilized PDMDAAC-SiO(2) films demonstrated effective immobilization of both indicators.
• ATR spectrometry revealed distinct spectroscopic responses for Fe(2+) and H(+) at their respective optimal wavelengths.
• The sensor films exhibited a linear detection range of 2.5x10(-6)-5.0x10(-5) M for Fe(2+) and pH 4.1-6.8 for H(+).
• High sensitivity was achieved, with values of 2.2x10(4) DeltaA/M for Fe(2+) and 0.583 DeltaA/pH for H(+).

Conclusions:

• The PDMDAAC-SiO(2) composite thin films successfully immobilized Ferrozine and HPTS for simultaneous Fe(2+) and pH sensing.
• The developed sensor films offer a promising platform for sensitive and selective spectroscopic detection of iron and pH in solutions.
• This approach holds potential for applications in environmental monitoring and chemical analysis requiring dual-analyte detection.