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.

Fast Preparation of Polydopamine Nanoparticles Catalyzed by Fe2+/H2O2 for Visible Sensitive Smartphone-Enabled Cytosensing

“…In recent years, smartphone-based biomedical devices have satisfactory feasibility of out-of-laboratory diagnostics and mobile data transfer, which have been widely applied into detection of uric acid, bovine serum albumin, trinitrotoluene, pH and nitrite, proteolytic activity, furfural, and copper­(II) ions. − Furthermore, this colorimetric biosensing strategy based on smartphone is low cost and simple to perform on-site, and the colorimetric results are rapidly read by red–green–blue (RGB) color images. Hence, the smartphone enabled colorimetric cytosensing has become a promising approach for point-of-care medical diagnosis.…”

Colorimetric Detection of an Airborne Remote Photocatalytic Reaction Using a Stratified Ag Nanoparticle Sheet

“…The colorimetric naked-eye detection, which requires only the human eyes, has great potential for portable and disposable sensor chips as both inexpensive diagnostic systems for home healthcare and outdoor or on the spot environmental testing. − Recently, a vapor-sensing device for low-molecular-weight gas was developed, which attracted the interest of researchers in many other fields, such as food science (e.g., a quality control of fresh food, fermented management, and design of flavors) and chemical engineering (e.g., monitoring the dry process in printing and coating technology, following a chemical reaction). , The approach introduced in this study will be classified into the one of these categories. The low-density molecules and radicals produced by the photocatalytic reaction process in the air are the target of high-sensitive detection.…”

A Versatile and Highly Selective Colorimetric Sensor for the Detection of Amines

“…[25] Although advances to colorimetric sensors have allowed for the identification and quantification of specific analytes, thesem ethods often involve the use of specialized equipment and are restricted to the detection of volatile amines, limiting their use as ag eneral amine colorimetric sensor.R ecent investigation into new negative photoswitches, termed donor-acceptor Stenhousea dducts (DASAs), revealed an avenuet oi ncreasing the versatility and selectivity of colorimetric detection of amines. [26,27] The ring opening of activated furans with secondary amines is ar apid and efficient reaction that produces DASAs, whichp ossess high molar absorptivity values (e lmax % 10 5 m À1 cm À1 ). [28][29][30] The facile synthesis of activated furans from commerciallya vailablea nd inexpensive startingm aterials coupled with the high e of the DASA productindicated the potential of activated furans as colorimetric sensors.…”