Novel color standards for digital color analysis of optochemical sensor arrays

Simple colorimetric copper(II) sensor - Spectral characterization and possible applications

New o-hydroxyazocompound L bearing pyrrole residue was obtained in the simple synthetic protocol. The structure of L was confirmed and analyzed by X-ray diffraction. It was found that new chemosensor can be successfully used as copper(II) selective spectrophotometric regent in solution and can be also applied for the preparation of sensing materials generating selective color signal upon interaction with copper(II). Selective colorimetric response towards copper(II) is manifested by a distinct color change from yellow to pink. Proposed systems were effectively used for copper(II) determination at concentration level 10^-8 M in model and real samples of water.

Smartphone-based colorimetric determination of fluoride anions using polymethacrylate optode

We developed a new transparent polymer optode based on polymethacrylate with Zr(IV) and alizarin red complex immobilized into it for digital colorimetric and solid-phase spectrophotometric determination of fluoride anions. The matrix changes its colour from purple to yellow after it contacts fluoride anion. We developed a processing algorithm for coloured images which helps calculate mean value for the RGB colour-coordinate system in a selected optode image and translates it into a fluoride concentration value. The analytical signal of the suggested method has a linearity range of 0.1-30 mg⋅L^-1 with the detection limit 0.03 mg⋅L^-1. Compared to other methods, the modified polymethacrylate matrix is actually a ready-to-use colorimetric system offering rapid results for drinking water quality control.

Simple and Cost-Efficient Classification of Ballpoint Pen Inks Using Digital Color Analysis

We report here a simple and cost-effective technique for classification of the samples of writing inks based on their digital color analysis (DCA). The dynamics of artificial aging of writing inks under UV irradiation was studied by means of DCA for the first time. The color of ballpoint pen marks was recorded over time using an ordinary consumer DSLR camera. The inks were classified according to the parameters of their color degradation curves with precision superior to conventional Raman scattering method, which serves as a proof-of-concept of the proposed approach. The reported approach has broad prospects for implementation by criminalists for document investigation when document forgery is suspected. The proposed technique can be of interest not only in the field of forensic science but also for those who deal with dyes and dye-containing materials and their degradation over time as well as for the study of any processes, the evolution of which is reflected in a color change.