Spectroscopic Sensing with a Highly Transparent, Ion-Exchangeable Polymer Blend

A polymer blend formulation originally patented by the National Aeronaticautical and Space Administration (NASA) has been modified for use in spectroscopic sensing. The cured polymer blend is a mixture of poly(acrylic acid) in glutaraldehyde cross-linked poly(vinyl alcohol). We have optimized the composition and the casting of the blend for optical sensing. The blend has clear ultraviolet (UV) and visible spectral regions for direct spectroscopic sensing, and it is an excellent absorber of many inorganic and organic cations from aqueous solution. The kinetics of the uptake of [Ru(BiPy)3]2+ and rhodamine 620 are presented as examples of complex ion preconcentration by the blend. With only the polymer blend directly applied as a fiber-optic cladding, aqueous Cu2+ ion can be detected as low as 10−6 M by using a light-emitting diode at 810 nm as a light source. A blend-clad fiber-optic sensor can be regenerated at least 25× without significant deterioration. The polymer blend can also trap hydrophobic compleximetric reagents added during the curing of the cross-linked blend. A prototype compleximetric dye-based evanescent-wave fiber-optic sensor using 1-(2'-pyridylazo)-2-naphthol was developed to detect aqueous Co2+ with a red HeNe laser light source. The Co2+ ion could be detected as low as 10−7 M.

[1]  J. Seferis.  Refractive Indices of Polymers , 1999 .

[2]  Richard E. Russo,et al.  Core-Based Intrinsic Fiber-Optic Absorption Sensor for the Detection of Volatile Organic Compounds , 1995 .

[3]  R. Cattrall,et al.  Nafion-based optode for the detection of metal ions in flow analysis , 1996 .

[4]  Daniel C. Harris,et al.  Quantitative Chemical Analysis , 1968, Nature.

[5]  Michael D. DeGrandpre,et al.  Polymer-coated cylindrical waveguide absorption sensor for high acidities , 1989 .

[6]  T. P. Jones,et al.  Optical pH sensor based on the chemical modification of a porous polymer film , 1988 .

[7]  Lloyd W. Burgess,et al.  A Fiber-Optic FT-NIR Evanescent Field Absorbance Sensor , 1990 .

[8]  J. Aznárez,et al.  Some observations on the spectrophotometric determination of zinc with 1-(2-pyridylazo)-2-naphthol, diphenylguanidine, and cetyltrimethylammonium bromide, in chloroform , 1989 .

[9]  Ramaier Narayanaswamy,et al.  Fibre-optic pH probe based on the use of an immobilised colorimetric indicator , 1984 .

[10]  Lloyd W. Burgess,et al.  Long path fiber-optic sensor for evanescent field absorbance measurements , 1988 .

[11]  L. Burgess,et al.  Study of Analyte Diffusion into a Silicone-Clad Fiber-Optic Chemical Sensor by Evanescent Wave Spectroscopy , 1995 .

[12]  W. Heineman,et al.  Chemical Sensors for Radiopharmaceuticals , 1993 .

[13]  Chris W. Brown,et al.  Fiber-optic pH sensor based on evanescent wave absorption spectroscopy , 1993 .

[14]  W. Rudolf Seitz,et al.  Poly(vinyl alcohol) as a substrate for indicator immobilization for fiber-optic chemical sensors , 1989 .

[15]  M. Valcárcel,et al.  Integrated reaction/spectrophotometric detection in unsegmented flow systems , 1988 .

[16]  K. Street,et al.  Determination of Copper in Tap Water Using Solid-Phase Spectrophotometry , 1994 .