A Voltammetric pH Sensor for Food and Biological Matrices

Abstract

<div>Measurement of pH is of fundamental importance in a wide range of environmental, biological and industrial applications. Glass electrode and litmus paper are widely used for this, but the former is difficult to miniaturize, prone to drift and fragile, the latter is inaccurate. This paper describes a pH sensor based on an indoaniline-derivative (4-((4-aminophenyl)imino)-2,6-dimethoxycyclohexa-2,5dien-1-one), which exploits alternating current voltammetry to measure pH in the range between 2 and 12 . The synthetized indoaniline-derivative was not genotoxic (A. cepa assay), and the sensor reliably measured pH in milk, tea, orange juice, blood, urine and saliva. Results were comparable with those obtained with a glass electrode calibrated with certified solutions (maximum relative standard deviation of 3 % and accuracy less than 0.2 pH unit). The sensor had negligible hysteresis, an almost Nernstian sensitivity (56 mV/pH) and was fully functional after a two-month storage. Sensor response showed a limited dependence on temperature (0.14 mV per pH unit and °C) and limited sensitivity to possible interferents such as lithium and sodium ions; its response to these was similar to that of a glass electrode, and was absent for ascorbic acid. </div>

Characterization of the Impact of Classical Cell‐culture Media on the Response of Electrochemical Sensors

“…These results confirm that the IrOx probe is virtually unaffected by the difference in media composition, whereas; the IrOx probe may be oxidised in presence of oxidant species (e. g. H 2 O 2 ) (Figure S3). Finally, pH sensors showed a wider dynamic range than the one needed for biological applications [31] that was tested here (between 5 and 8).…”

Biosensors for Biogenic Amines: A Review

“…Signals are generated during biochemical reactions and are measured using suitable transducers. They are based on chemically modified electrodes where conducting or semiconducting materials are coated with a biochemical film [ 62 , 63 ]. Food matrices are known to have many electroactive interferents, with ascorbic acid being one of the most common interferents.…”

“…Besides the presence of ascorbic acid in food matrices, uric acid is also reported to be an interfering species. However, the configuration and disposition of the biosensor can provide better selectivity, thus helping discard the possibility of interference [ 63 ]. Among the transducers that fall in this class, the amperometric, conductometric, impedimetric, and potentiometric types of sensors are further highlighted below.…”