Scavenging of SO4− radical anions by mono- and dicarboxylic acids in the Mn(II)-catalyzed S(IV) oxidation in aqueous solution

Activated sodium peroxydisulfate has the potential to in situ destruct many organic contaminants because of the generation of the stronger oxidant sulfate radical. From photochemical activation of peroxydisulfate in flash-photolysis experiments, the bimolecular rate constants for the reaction of sulfate radical with glyphosate (1.6 × 10(8) M(-1) s(-1)) and paraquat (1.2 × 10(9) M(-1) s(-1)) at 25 °C were obtained. Thermal activation of peroxydisulfate was shown to degrade the herbicides clomazone, paraquat, and glyphosate. Although the herbicide degradation was observed to take place in less than 1 h, the mineralization of the organic carbon required longer reaction times, because of the formation of stable organic intermediates. For similar initial total organic carbon (TOC) values, TOC profiles were similar for experiments with different substrates (the herbicides, humic acids, and a mixture of glyphosate and humic acids), which indicates that the mineralization of all of the samples is limited by the production of SO(4)(•) (-) radicals. A linear correlation between the initial amount of SO(4)(•) (-) needed per mole of C and the average oxidation state was found.

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“…• -radicals (19). A similar behavior was observed for experiments at 80°C with 2 Â 10 -3 M PS and 1 Â 10 -4 M PQ or 1 Â 10 -4 M CLO.…”

Section: Resultssupporting

confidence: 79%

Degradation of the Herbicides Clomazone, Paraquat, and Glyphosate by Thermally Activated Peroxydisulfate

Kirmser

Mártire

González

et al. 2010

J. Agric. Food Chem.

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“…Alternatively, quenching of SO4 •can occur via the carboxylic acid moiety of Hcy (equation 3and (4)). 42…”

Section: Homocysteine Detectionmentioning

confidence: 99%

Cathodic Quantum Dot Facilitated Electrochemiluminescent Detection in Blood

2018

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The expansion of electrochemical sensors to biomedical applications at point of care requires these sensors to undergo analysis without any pre-treatment of extraction. This poses a major challenge for all electrochemical sensors including electrochemiluminescent (ECL) based sensors. ECL offers many advantages for biomedical applications however; obtaining results from complex matrices has proven to be a large hurdle for the application of ECL sensors within this field. This work demonstrates the potential of cathodic ECL to detect and quantify homocysteine with 0.1 nM limit of detection, which is associated with hyperhomocysteinemia, in blood. This near infrared quantum dot (NIR QD) based ECL sensor displays good linearity allowing for rapid detection and providing a basis for exploitation of ECL based sensors for biomedical diagnostics utilising homocysteine as a model cathodic co-reactant. This work will lay the foundations for future developments in biosensing and imaging fields and stands as an initial proof of concept for the utilization of cathodic ECL technologies for biomedical applications once the limits of detection within clinically relevant levels has been achieved. This work illustrates the potential of cathodic ECL sensors, using Hcy as a model complex, for the detection of biomolecules. EXPERIMENTAL Materials Qdot® 800 ITK™ organic quantum dots, (1 μM in decane) were obtained from Invitrogen. Lumidot™ 560 and 640 nm QDs, (5 mg/mL in toluene), chitosan (medium molecular weight, 75-85 % de-acetylated), and all other chemicals were purchased from Sigma-Aldrich. All solutions were prepared in milli-Q water (18 mΩ cm). Bovine whole blood samples utilised within this study were obtained from Wishaw Abattoir Ltd following University of Strathclyde ethical approval. These were stored in aliquots at-20 ºC. Aliquots were defrosted at room temperature on the day of analysis and used immediately. Instrumentation A CH instrument model 760D electrochemical analyser using a standard 3 electrode setup including a 3 mm diameter GC working electrode, Pt wire counter electrode and Ag/AgCl 3 M KCl reference electrode purchased from IJ Cambria Scientific Ltd (UK) was utilised to record all electrochemical measurements. GC electrodes were cleaned following the pro-ASSOCIATED CONTENT Supporting Information Supporting material includes ECL responses for the interactions with reactive oxygen species (Figure S1), ECL responses for 1 mM K2S2O8 in blood with the Stern-Volmer and modified Stern-Volmer plots for this data (Figure S2). The ECL dependence for the interferents given in Figure 6 (Figure S3). Chromatographic experimental details are also included (Figure S4). This material is available free of charge via the Internet at http://pubs.acs.org.

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“…It may be pointed out that the relation (21) between B and k inh has been examined generally for aliphatic compounds only. Likewise, a relationship between k inh and bond dissociation energy 5a,b, , and between log k inh and bond dissociation energy in an Evans–Polanyi type correlation 5a,b were mostly for aliphatic compounds. Similarly, Khursan et al too analyzed the experimental rate constants of the sulfate radical anions with C─H bonds of aliphatic compounds with Denisov's intersecting parabolas method.…”

Section: Discussionmentioning

confidence: 92%

“…For example, Grgic et al in their study on scavenging of SO 4 − radical anions by mono‐ and dicarboxylic acids in the Mn(II)‐catalyzed S(IV) oxidation in aqueous solution found malic (pH 9, k inh = 1.5 × 10 6 L mol −1 s −1 ) and malonic (pH 9, k inh = 5.5 × 10 6 L mol −1 s −1 ) acids to show no inhibition despite high k inh values. No exact reason could be assigned for this behavior . It was suggested that there could be additional reaction, which may form peroxy radicals which might oxidize sulfur(IV) and hinder the inhibition.…”

Section: Discussionmentioning

confidence: 99%

Inhibition of Aquated Sulfur Dioxide Autoxidation by Aliphatic, Acyclic, Aromatic, and Heterocyclic Volatile Organic Compounds

Meena

Dhayal

Rathore

et al. 2017

Int J of Chemical Kinetics

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The oxidation of dissolved sulfur dioxide, sulfur(IV), by oxygen proceeds through the involvement of sulfoxy radicals among which sulfate radical anion is the main chain carrier. When organics are present, they inhibit the oxidation of sulfur(IV) via scavenging of SO4− radicals. In contrast to previous studies, which were limited mostly to aliphatic compounds, this paper presents the results of the effect of 13 new volatile organic compounds (VOCs) including aromatic and heterocyclic on uncatalyzed sulfur(IV) autoxidation at pH 8.2 and 25°C. In all cases, the kinetics was first order in the presence and absence of VOCs and experimental rate law was Eq. (1). trueright−d[normalSfalse( IV false)]/normaldt=k obs []normalSfalse( IV false)=ko[]normalSfalse( IV false)/{}1+Bfalse[ Inh false]where −d[S(IV)]/dt is the rate of sulfur(IV) disappearance, kobs is the first‐order rate constant in the presence of inhibitor, ko is the first‐order rate constant in the absence of inhibitor, [S(IV)] is concentration of sulfur(IV) at time, t, and B is an inhibition parameter. VOCs cause inhibition by scavenging sulfate radical anions, which propagate the autoxidation chain. An analysis of B (Eq. (1)) and kinh (Eq. (2)) values for 21 aliphatic, aromatic, acyclic, and heterocyclic organic compounds showed that these to be related by Eq. (3) for a subgroup and Eq. (4) for b subgroup. trueright SO 4−+ VOC 0.33em⟶k inh 0.33em SO 42−+ VOC a subgroup (benzamide, 2,2‐dimethyl‐1‐propanol, 1‐hexanol, methanol, ethanol, 1‐propanol, 2‐ propanol, 1‐butanol, 2‐butanol, ethylene glycol, rebaudioside A) truerightB=()0.87±0.21×10−30.16emk inh b subgroup (o‐toluic acid, m‐toluic acid, p‐toluic acid, 4‐hydroxybenzoic acid, 1‐heptanol, glycerol, sucralose, acesuifame K, glycine, 3‐pentanol) truerightB=()1.2±0.3×10−30.16emk inh

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Scavenging of SO4− radical anions by mono- and dicarboxylic acids in the Mn(II)-catalyzed S(IV) oxidation in aqueous solution

Cited by 25 publications

References 23 publications

Degradation of the Herbicides Clomazone, Paraquat, and Glyphosate by Thermally Activated Peroxydisulfate

Degradation of the Herbicides Clomazone, Paraquat, and Glyphosate by Thermally Activated Peroxydisulfate

Cathodic Quantum Dot Facilitated Electrochemiluminescent Detection in Blood

Inhibition of Aquated Sulfur Dioxide Autoxidation by Aliphatic, Acyclic, Aromatic, and Heterocyclic Volatile Organic Compounds

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