title: Sol-gel based optical carbon dioxide sensor employing dual luminophore referencing for application in food packaging technology.
abstract: An optical sensor for the measurement of carbon dioxide in Modified Atmosphere Packaging (MAP) applications has been developed. It is based on the fluorescent pH indicator 1-hydroxypyrene-3,6,8-trisulfonate (HPTS) immobilised in a hydrophobic organically modified silica (ormosil) matrix. Cetyltrimethylammonium hydroxide was used as an internal buffer system. Fluorescence is measured in the phase domain by means of the Dual Luminophore Referencing (DLR) sensing scheme which provides many of the advantages of lifetime-based fluorometric sensors and makes it compatible with established optical oxygen sensor technology. The long-term stability of the sensor membranes has been investigated. The sensor displays 13.5 degrees phase shift between 0 and 100% CO2 with a resolution of better than 1% and a limit of detection of 0.08%. Oxygen cross-sensitivity is minimised (0.6% quenching in air) by immobilising the reference luminophore in polymer nano-beads. Cross-sensitivity towards chloride and pH was found to be negligible. Temperature effects were studied, and a linear Arrhenius correlation between ln k and 1/T was found. The sensor is stable over a period of at least seven months and its output is in excellent agreement with a standard reference method for carbon dioxide analysis.
authors.affiliation: Department of Physics/National Centre for Sensor Research, Dublin City University, Ireland.
authors.forename: Christoph
authors.initials: C
authors.lastname: von Bultzingslöwen
authors.forename: Aisling K
authors.initials: AK
authors.lastname: McEvoy
authors.forename: Colette
authors.initials: C
authors.lastname: McDonagh
authors.forename: Brian D
authors.initials: BD
authors.lastname: MacCraith
authors.forename: Ingo
authors.initials: I
authors.lastname: Klimant
authors.forename: Christian
authors.initials: C
authors.lastname: Krause
authors.forename: Otto S
authors.initials: OS
authors.lastname: Wolfbeis
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D019649:Food Industry; D018857:Food Packaging; D005782:Gels; D049449:Luminescence; D013050:Spectrometry, Fluorescence / Q000295:instrumentation / Q000379:methods
chemical_list: D005782:Gels; D002245:Carbon Dioxide