A new electrochemical sensor for OH radicals detection

Poly(methylene blue)-modified electrode for indirect electrochemical sensing of OH radicals and radical scavengers

“…This pro-oxidative capacity of ascorbic acid is in accordance with previous results reported in literature (Berger et al 1997, Carr and Frei 1999, Valko et al 2005. However, in the few studies related to chemically modified electrodes (CMes) for OH · sensing (Gualandi et al 2014, Gualandi and Tonelli 2013, Scholz et al 2007, Hilgemann et al 2010, it is the first time that such behavior is observed concerning this pro-oxidative effect of AA when it is used as an antioxidant. Thus, in these cases, low AA levels should be maintained.…”

“…In this sense, electrochemical assays are promising tools: suitable for fast analyses, based on inexpensive instrumentation and with simple operation protocols (Prieto-Simón et al 2008). Additionally, studies propose the use of chemically modified electrodes (CMEs) as a simple electrochemical approach to sense ROS and radical scavengers, with DNA, selfassembled monolayers of thiols, polyphenol films, and conducting polymers (CPs) (Scholz et al 2007, Liu et al 2005, Mello et al 2006, Hilgemann et al 2010, Wu et al 2012, Gualandi and Tonelli 2013, Gualandi et al 2014 as electrode modifiers. The ROS may attack the CME and the extent of the modifier destruction can be evaluated directly (in this case, when an electroactive layer is monitored) or using an electrochemical probe in solution (when a non-electroactive layer is used).…”

Insight on the fundamentals of advanced oxidation processes. Role and review of the determination methods of reactive oxygen species

“…Although quantification of the products concentration has been performed either with absorbance, fluorescence and electrochemical detectors, the measurements based on absorbance are the most frequently used. The quantification of •OH with this method has been successfully achieved in Fenton systems; electrochemical methods such as pulsed plasma power and electrochemical oxidation; processes based on ultrasound with or without photocatalysts and hydrodynamic cavitation . Most studies concern optimization of the operating conditions and the influence of many variables such as electrode materials, sonolysis frequency, pH, the presence of other organic compounds in the solution, concentration of SA, etc.…”

“…correlated the amperometric signal recorded in cyclic voltammetry with the luminescence generated as a consequence of the reaction between Phth and •OH. In a different work, Gualandi and Tonelli used an electrode covered by a polyphenol film and the redox pair Ru(NH 3 ) 6 3+ /Ru(NH 3 ) 6 2+ . The relationship between the uncovered area (reaction ), as a consequence of the reaction between the polyphenol film and the •OH produced in Fenton and photocatalysis processes, and the concentration of •OH was established through the chromatographic method using SA.…”

“…Indirect methods based on the use of probes or scavengers have been developed and applied to selectively detect ROS generated in AOPs, since their direct determination is only feasible on the sub‐millisecond timescale owing to their short lifetime (10 −10 s for •OH) . These methods comprise obtaining a compound that reacts selectively, sensitively and unambiguously with the ROS under study, and then the quantification of either the loss of a reagent or the accumulation of a product.…”