Electrochemical Analysis

Quantitative analyses of olive oil for lipophilic antioxidants, such as α-tocopherol and phenolics, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), which was bicontinuously composed of saline and toluene microphases with a surfactant system. Lipophilic antioxidants in oils were directly monitored in BME solutions using a lipophilic, fluorinated nanocarbon-film electrode (F−ECR). The combination of a well-balanced BME and extremely biased electrodes, such as strongly hydrophilic indium/tin oxide and strongly lipophilic (hydrophobic) F−ECR, allowed individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without any required extraction. Furthermore, values for the charge Q, integrated from observed currents, showed good linear relationships with the results of conventional assays for antioxidant activity, namely, total phenolics and oxygen radical absorbance capacity assays, even with practical food samples. This proposed methodology provided a very simple, rapid, easily serviceable, and highly reproducible analysis that possesses great potential for applications to a wide range of chemical mixtures, in terms of analyte and media, beyond food oils.

Li[Ni1/3Mn1/3Co1/3]O2/graphite, Li[Ni0.5Mn0.3Co0.2]O2/graphite and Li[Ni0.6Mn0.2Co0.2O2]/graphite pouch cells were examined with and without electrolyte additives using the ultra high precision charger at Dalhousie University, electrochemical impedance spectroscopy, gas evolution measurements and “cycle-store” tests. The electrolyte additives tested were vinylene carbonate (VC), prop-1-ene-1,3-sultone (PES), pyridine-boron trifluoride (PBF), 2% PES + 1% methylene methanedisulfonate (MMDS) + 1% tris(trimethylsilyl) phosphite (TTSPi) and 0.5% pyrazine di-boron trifluoride (PRZ) + 1% MMDS. The charge end-point capacity slippage, capacity fade, coulombic efficiency, impedance change during cycling, gas evolution and voltage drop during “cycle-store” testing were compared to gain an understanding of the effects of these promising electrolyte additives or additive combinations on the different types of pouch cells. It is hoped that this report can be used as a guide or reference for the wise choice of electrolyte additives in Li[Ni1/3Mn1/3Co1/3]O2/graphite, Li[Ni0.5Mn0.3Co0.2]O2/graphite and Li[Ni0.6Mn0.2Co0.2O2]/graphite pouch cells and also to show the shortcomings of particular positive electrode compositions.

Qualitative and quantitative analyses of hydrophilic and lipophilic antioxidants, such as polyphenols, by simple electrochemical measurements were conducted in a bicontinuous microemulsion (BME), in which water and oil phases coexisted bicontinuously on a microscopic scale. Hydrophilic and lipophilic antioxidants were individually monitored in the same BME solution using a hydrophilic indium tin oxide (ITO) electrode and a lipophilic fluorinated nanocarbon film electrode (F-ECR), respectively. The combination of well-balanced BME and extremely biased electrodes, such as ITO and F-ECR, in terms of hydrophilic−lipophilic balance allowed us to achieve individual monitoring of hydrophilic and lipophilic antioxidants in the same BME solution without extraction. Furthermore, the antioxidant activities of functional liquid foods, such as coffee and olive oil, were also evaluated by means of electrochemical measurements in BME solutions containing analytes in concentrations of several percent. The technique we propose provides a very simple, rapid, easily serviceable, and highly reproducible analysis and can be extended to a wide range of analytes and media.

Electronics and chemistry are subjects characterized by their appreciable contribution for the well-being and comfort of humanity. Technological innovations on health, food safety and environmental conservation are highlighted among these contributions. Contemporary lifestyle has accelerated demand for new technological innovations to meet current challenges. Electrochemical analysis systems, particularly, are considered highly complex and, in most cases, delegated to experts. Thus, it is important to conduct research to guarantee timely solutions. Currently, capacitive sensor developments have been presented, taking advantage of the relationship between ionic activity from chemical solutions with the energy stored in the capacitor. Furthermore, due to easy implementation and because they are naturally non-invasive, capacitive sensors represent a technological option of great promise in electrochemical analysis systems. This research study aims at providing an inexpensive electronic tool of rapid implementation to allow determination in situ of concentration of an aqueous solution. All this due to the need to increase competitiveness in agribusinesses, specifically on the automation outlook, given that with support of electronics and instrumentation, many processes and procedures exclusively developed in laboratories, could be transferred to the end user. Implementing the proposed system allows to demonstrate its potential use as a quality control tool, e.g., in beverage dispensers, tasting systems incorporated into the f transport of raw materials in liquid state and other agribusiness applications.