A Rico-Yuste, V Gonzalez-Vallejo, E Benito-Peña… – Analytical Chemistry, 2016
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 furfural-sensitive indicator monomer, 2-hydroxymethylmethacrylate as co-monomer and ethylene dimethylmethacrylate (EDMA) as cross-linker. The sensing mechan ism is based on the Stenhouse reaction in which aniline and furfural react in acidic media with 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 ageing. 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 pre-loaded calibration curves. The method has been applied to determination of furfural in ale 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.
… diameter at the common branch, 1.6 mm diameter at each leg). Our system uses a high-intensity white light LED as light source (SL1-LED, StellarNet, Fla., USA). The mini-spectrometer acquisition and signal display is provided by …
