1 research outputs found
Furfural Determination with Disposable Polymer Films and Smartphone-Based Colorimetry for Beer Freshness Assessment
We have developed disposable color-changing
polymeric films for
quantification of furfurala freshness indicatorin
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<sup>–1</sup> range, with a detection limit of 12
μg L<sup>–1</sup>, 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
(<i>r</i> > 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