Using a Smartphone in the Identification and Classification of Natural Mineral Waters by Color Measurements of Indicator Papers

A test device based on cellulose paper is proposed for the identification and classification of natural mineral waters. It contains indicator zones for determining total hardness, alkalinity, and pH of water, and also concentrations of chlorides and sulfates. The colorimetric parameters of the indicator zones of the test device after its contact with test water are determined using a smartphone. The analytical signal (A(r)) is presented by the values of the colorimetric parameters of each indicator zone in the RGB system: A(r) = root(R-0 - R-x)(2) + (G(0) - G(x))(2) + (B-0 - B-x)(2). The data array is processed by principal component analysis and hierarchical cluster analysis using the XLSTAT software. The identification and classification of 33 natural mineral waters (eight of which were carbonated) was performed.