Fibre-optic fluorescing sensor for ammonia

Wolfbeis, Otto S.; Posch, Hermann E.

doi:10.1016/0003-2670(86)80060-5

Cited by 108 publications

(34 citation statements)

References 14 publications

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“…From these data it appears that for all three films the overall process is exothermic and associated with a significant loss of entropy, which is not surprising given the nature of Eqs. (3) and (4). Similar results were obtained in our previous study of colorimetric plastic thin-film sensors for carbon dioxide, in which the same plastic media were used as here.…”

Section: Film Spectral Changes As a Function Of Pnmsupporting

confidence: 88%

Plastic colorimetric film sensors for gaseous ammonia

1995

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Abstract. The preparation and characterization of three different plastic thinfilm colorimetric sensors for gaseous ammonia is described. In the film sensors, the neutral form of a pH-sensitive dye (Bromophenol Blue, Bromocresol Green or Chlorophenol Red) was encapsulated in a plastic medium, either poly(vinyl butyral) or ethylcellulose plasticized with tributyl phosphate. Each of these film optodes gave a reproducible and reversible response towards gaseous ammonia. The sensitivity of the film sensors towards ammonia was found to be strongly dependent upon the pK a of the encapsulated dye. Thus, the film with Chlorophenol Red (pK a = 6.25), proved to be very insensitive (operating range: 0.29% < %NH 3 < 100%), whereas the film with Bromophenol Blue (pK a = 4.1), was much more sensitive (operating range: 0.0003% < %NH a < 0.11%). The sensitivity of a plastic film sensor decreased markedly with increasing operating temperature and the 90% response (15-38 s) and recovery (820-127s) times were slow and activation-controlled.

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Section: Film Spectral Changes As a Function Of Pnmsupporting

confidence: 88%

Plastic colorimetric film sensors for gaseous ammonia

1995

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“…The fluorescence of HPTS and its application have been studied for nearly half a century. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Förster, 1,2 Weller 3,4 and co-workers first measured the pH-dependent fluorescence of HPTS, due to its ROH* and RO À * forms, and established indirect methods of excited state proton transfer rate determination. Excited state proton transfer from HPTS has since been studied directly.…”

Section: Introductionmentioning

confidence: 99%

“…For example, HPTS has been used to study the process of carbon monoxide binding to haemoglobin; 7 as a pH probe of liposome interiors and surfaces; 8 and in sensors of pH, 9,10 carbon dioxide 11 and ammonia. 12 In addition to the pH dependence of HPTS fluorescence, the maximum of the ROH* fluorescence is solvent-dependent. However, there have been only a few studies of this solvent dependence.…”

Section: Introductionmentioning

confidence: 99%

Solvent dependence of pyranine fluorescence and UV-visible absorption spectra

Barrash-Shiftan

Brauer

Pines

1998

J. Phys. Org. Chem.

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Fluorescence and UV-visible absorption spectra of HPTS (8-hydroxy-1,3,6-pyrenetrisulphonic acid trisodium salt, pyranine) were measured in a variety of solvents. Fluorescence maxima (in kcal mol -1 ) can be correlated with the Kosower Z parameter (r = 0.901), the Dimroth-Reichardt E T (30) parameter (r = 0.900) and the Winstein Y parameter (r = 0.916) using one-parameter fits. Good correlations (r = 0.98) were obtained for HPTS fluorescence in ethanol-water mixtures using the Y, Y OTs and Z parameters. Fluorescence maxima of HPTS in aqueous sulphuric acid solutions gave an excellent correlation with Y OTs (r = 0.991). Multi-parameter correlations, indicating the significance of specific solvent interactions, were also studied. In addition, fluorescence maxima correlate well with maximum/minimum ratios obtained from UV-visible absorption experiments. Results can be applied in the use of HPTS as a molecular probe of solvent environments and for extension of the Y OTs scale in acidic solutions. HPTS is a unique molecular probe, not only because of its photoacidic properties and its widespread use as a pH-sensitive biosensor, but also because of its relative stability in acidic environments.

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“…Fiber optic sensors have since then found applications in chemical [1-4], biochemical [4-8], biomedical and environmental [9-12] sensing.…”

Section: Introductionmentioning

confidence: 99%

Fiber Optic Sensors For Detection of Toxic and Biological Threats

El-Sherif

Bansal

Yuan

2007

Sensors

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Protection of public and military personnel from chemical and biological warfare agents is an urgent and growing national security need. Along with this idea, we have developed a novel class of fiber optic chemical sensors, for detection of toxic and biological materials. The design of these fiber optic sensors is based on a cladding modification approach. The original passive cladding of the fiber, in a small section, was removed and the fiber core was coated with a chemical sensitive material. Any change in the optical properties of the modified cladding material, due to the presence of a specific chemical vapor, changes the transmission properties of the fiber and result in modal power redistribution in multimode fibers. Both total intensity and modal power distribution (MPD) measurements were used to detect the output power change through the sensing fibers. The MPD technique measures the power changes in the far field pattern, i.e. spatial intensity modulation in two dimensions. Conducting polymers, such as polyaniline and polypyrrole, have been reported to undergo a reversible change in conductivity upon exposure to chemical vapors. It is found that the conductivity change is accompanied by optical property change in the material. Therefore, polyaniline and polypyrrole were selected as the modified cladding material for the detection of hydrochloride (HCl), ammonia (NH3), hydrazine (H4N2), and dimethyl-methl-phosphonate (DMMP) {a nerve agent, sarin stimulant}, respectively. Several sensors were prepared and successfully tested. The results showed dramatic improvement in the sensor sensitivity, when the MPD method was applied. In this paper, an overview on the developed class of fiber optic sensors is presented and supported with successful achieved results.

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Fibre-optic fluorescing sensor for ammonia

Cited by 108 publications

References 14 publications

Plastic colorimetric film sensors for gaseous ammonia

Plastic colorimetric film sensors for gaseous ammonia

Solvent dependence of pyranine fluorescence and UV-visible absorption spectra

Fiber Optic Sensors For Detection of Toxic and Biological Threats

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