title: Furfural Determination with Disposable Polymer Films and Smartphone-Based Colorimetry for Beer Freshness Assessment.
abstract: We have developed disposable color-changing polymeric films for quantification of furfural-a freshness indicator-in beer using a smartphone-based reader. The films are prepared by radical polymerization of 4-vinylaniline, as a furfural-sensitive indicator monomer, 2-hydroxymethyl methacrylate as a comonomer, and ethylene dimethyl methacrylate (EDMA) as a cross-linker. The sensing mechanism is based on the Stenhouse reaction in which aniline and furfural react in acidic media with the generation of a deep red cyanine derivative, absorbing at 537 nm, which is visible to the naked eye. The colorimetric response has been monitored using either a portable fiber-optic spectrophotometer or the built-in camera of a smartphone. Under the optimized conditions, a linear response to furfural in beer was obtained in the 39 to 500 μg L(-1) range, with a detection limit of 12 μg L(-1), thus improving the performance of other well-established colorimetric or chromatographic methods. The novel films are highly selective to furfural, and no cross-reactivity has been observed from other volatile compounds generated during beer aging. A smartphone application (app), developed for Android platforms, measures the RGB color coordinates of the sensing membranes after exposure to the analyte. Following data processing, the signals are converted into concentration values by preloaded calibration curves. The method has been applied to determination of furfural in pale lager beers with different storage times at room temperature. A linear correlation (r > 0.995) between the storage time and the furfural concentration in the samples has been confirmed; our results have been validated by HPLC with diode-array detection.
authors.affiliation: Department of Analytical Chemistry and ‡Department of Organic Chemistry, Faculty of Chemistry, Complutense University of Madrid , Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Rico-Yuste
authors.affiliation: Department of Analytical Chemistry and ‡Department of Organic Chemistry, Faculty of Chemistry, Complutense University of Madrid , Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: González-Vallejo
authors.affiliation: Department of Analytical Chemistry and ‡Department of Organic Chemistry, Faculty of Chemistry, Complutense University of Madrid , Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Benito-Peña
authors.affiliation: Department of Analytical Chemistry and ‡Department of Organic Chemistry, Faculty of Chemistry, Complutense University of Madrid , Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Tomás
authors.initials: T
authors.lastname: de Las Casas Engel
authors.affiliation: Department of Analytical Chemistry and ‡Department of Organic Chemistry, Faculty of Chemistry, Complutense University of Madrid , Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Orellana
authors.affiliation: Department of Analytical Chemistry and ‡Department of Organic Chemistry, Faculty of Chemistry, Complutense University of Madrid , Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: María Cruz
authors.initials: MC
authors.lastname: Moreno-Bondi
mesh_terms: D001515:Beer / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D003124:Colorimetry / Q000295:instrumentation* / Q000379:methods*; D005662:Furaldehyde / Q000032:analysis*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D000068997:Smartphone
chemical_list: D011108:Polymers; D005662:Furaldehyde