Here, we report on the use of electrochemical methods for the detection of volatiles fatty acids (VFAs), namely acetic acid. We used tetra-tert-butyl phthalocyanine (PcH2-tBu) as the sensing material and investigated its electroanalytical properties by means of cyclic voltammetry (CV) and square wave voltammetry (SWV). To realize the electrochemical sensing system, the PcH2-tBu has been dropcast-deposited on carbon (C) orgold (Au)screen-printed electrodes (SPEs) and characterized by cyclic voltammetry and scanning electron microscopy (SEM). The SEM analysis reveals that the PcH2-tBu forms mainly aggregates on the SPEs. The modified electrodes are used for the detection of acetic acid and present a linear current increase when the acetic acid concentration increases. The Cmodified electrode presents a limit of detection (LOD) of 25.77 mM in the range of 100 mM–400 mM, while the Aumodified electrode presents an LOD averaging 40.89 mM in the range of 50 mM–300 mM. When the experiment is realized in a buffered condition, theCmodified electrode presents a lower LOD, which averagesthe 7.76 mM. A pronounced signal decay attributed to an electrode alteration is observed in the case of the gold electrode. This electrode alteration severely affects the coating stability. This alteration is less perceptible in the case of the carbon electrode.

In the current work, accurate quantification over 10 to 10 DNA copies has been successfully achieved for the first time by real-time electrochemical PCR. This has been made possible thanks to the combined use of a fully automated house-built electrochemical qPCR device, optimized for parallel heating and electrochemical monitoring of up to 48 PCR solutions, and the appropriate selection of a DNA intercalating redox probe retaining a strong affinity binding to ds-DNA at the PCR measurement temperature of 72 °C (corresponding to the PCR elongation step). This has also been achieved through the identification of the key parameters governing the onset electrochemical signal decrease and amplitude signal decrease as a function of the PCR cycle for a given DNA intercalating redox probe, thus allowing us to predict the electrochemical PCR kinetic plots from the values of the DNA affinity binding constant determined as a function of temperature. To the best of our knowledge, the analytical performances of the current electrochemical qPCR outperform all of those previously published, in terms of detection limit, dynamic range, reproducibility and melting curve analysis compared to that achieved on a commercialized bench-top fluorescence-based qPCR instrument.