Optical pH sensor based on the chemical modification of a porous polymer film

Journal Article · Tue Mar 01 00:00:00 EST 1988 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac00156a006· OSTI ID:7247968

Jones, T P; Porter, M D

A new approach to the design and construction of an optical pH sensor has been developed by immobilizing a direct azo dye at a porous cellulosic polymer film. This sensor was fabricated by binding Congo Red to a cellulose acetate film that had previously been subjected to an exhaustive base hydrolysis. Advantageous features of the design include (1) a rapid equilibration time (< 1.3 s), (2) a large dynamic range (> 4 pH units), and (3) ease of fabrication. The rapid response results from the porous structure of the polymeric support, which minimizes barriers to mass transport. The large dynamic range results from both the polyprotic acid-base reactivity of Congo Red and the large optical absorptivities of its various ionic forms. Furthermore, these results indicate that a variety of optical sensors which exhibit a rapid and sensitive response for the analysis of pH can be easily fabricated by immobilizing carefully selected direct dyes at porous polymeric substrates such as hydrolyzed cellulose acetate.

• Research Organization: Iowa State Univ., Ames (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 7247968
• Journal Information: Anal. Chem.; (United States), Vol. 60:5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
OPTICAL SPECTROMETERS
DESIGN
FABRICATION
PH VALUE
MEASURING METHODS
ABSORPTION SPECTROSCOPY
ACETATES
AZO DYES
CELLULOSE
EXPERIMENTAL DATA
ORGANIC POLYMERS
THIN FILMS
AZO COMPOUNDS
CARBOHYDRATES
CARBOXYLIC ACID SALTS
DATA
DYES
FILMS
INFORMATION
MEASURING INSTRUMENTS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
POLYMERS
POLYSACCHARIDES
SACCHARIDES
SPECTROMETERS
SPECTROSCOPY
400102* - Chemical &amp; Spectral Procedures