Chemometric-Assisted Litmus Test: One Single Sensing Platform Adapted from 1–13 to Narrow pH Ranges

Abstract

A novel 3 × 4 colorimetric sensing platform, named the chemometric-assisted litmus test (CLT), has been developed by covalently anchoring commercial pH indicators to ethylene vinyl alcohol (EVOH). The proposed device can be exploited for pH determinations in a wide range from 1 to 13 and in specific narrow ranges, achieving sufficient accuracy and errors below 0.5 pH units. The experimental procedure is simple, quick and reliable; equilibration is reached in less than 2 h, CLT pictures are acquired by a camera, and data treatment is performed applying chemometric techniques such as principal component analysis (PCA) and partial least square regression (PLS) to RGB indices.

Positively Charged Organosilanes Covalently Linked to the Silica Network as Modulating Tools for the Salinity Correction of pH Values Obtained with Colorimetric Sensor Arrays (CSAs)

“…pH is a key parameter that can be used as a probe for different phenomena like food spoilage [ 1 , 2 , 3 , 4 , 5 ], fermentation [ 6 , 7 , 8 , 9 ], ocean acidification [ 10 , 11 , 12 , 13 ], industrial processes, and so on [ 14 , 15 , 16 , 17 , 18 ]. Potentiometric determination with a glass electrode is traditionally the most important method used for pH measurement [ 19 ].…”

“…On the other hand, the need to perform in-field measurements contrasts with the batch nature of the glass electrode [ 13 ]. In the last few years, several efforts have been made to improve pH measurement [ 3 , 26 , 27 ]. Colorimetric sensor arrays (CSAs) [ 14 , 28 , 29 , 30 ] represent an economic and simple way to achieve this purpose [ 14 , 31 ].…”