scholarly journals Effect of filter extraction solvents on the measurement of the oxidative potential of airborne PM2.5

2021 ◽  
Author(s):  
Maria Chiara Pietrogrande ◽  
Dimitri Bacco ◽  
Arianna Trentini ◽  
Mara Russo
Keyword(s):  
Phosphate Buffer ◽  
Extraction Methods ◽  
Active Species ◽  
Experimental Measurements ◽  
Oxidative Potential ◽  
Preliminary Step ◽  
Lung Fluid ◽  
Redox Active ◽  
Extraction Solvents ◽  
Measured Volume

AbstractSolvent extraction of PM2.5 samples collected on the filter is a preliminary step for assessing the PM2.5 oxidative potential (OP) using cell-free assays, as the dithiothreitol (DTT) and the ascorbic acid (AA) assays. In this study, we evaluated the effect of the solvent choice by extracting ambient PM2.5 samples with different solvents: methanol, as organic solvent, and two aqueous buffers, i.e., phosphate buffer (PB) and Gamble’s solution (G), as a lung fluid surrogate solution. Both the measured volume-based OPVDTT and OPVAA responses varied for the different extraction methods, since methanol extraction generated the lowest values and phosphate buffer the highest. Although all the tested solvents produced intercorrelated OPVDTT values, the phosphate buffer resulted the most useful for OPDTT assessment, as it provided the most sensible measure (nearly double values) compared with other extractions. The association of the measured OPV values with PM chemical composition suggested that oxidative properties of the investigated PM2.5 samples depend on both transition metals and quinones, as also supported by additional experimental measurements on standard solutions of redox-active species.

scholarly journals On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals

2012 ◽  
Vol 12 (5) ◽  
pp. 11317-11350 ◽  
Author(s):  
J. G. Charrier ◽  
C. Anastasio
Keyword(s):  
Particulate Matter ◽  
Transition Metals ◽  
Fine Particulate Matter ◽  
Chemical Species ◽  
Past Research ◽  
Active Species ◽  
Oxidative Potential ◽  
Adverse Health Effects ◽  
Redox Active ◽  
Small Set

Abstract. The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. While most past research has indicated that the DTT assay is not sensitive to metals, our results show that seven out of the ten transition metals tested do oxidize DTT, as do three out of the five quinones tested. While metals are less efficient at oxidizing DTT compared to the most reactive quinones, concentrations of soluble transition metals in fine particulate matter are generally much higher than those of quinones. The net result is that metals appear to dominate the DTT response for typical ambient PM2.5 samples. Based on particulate concentrations of quinones and soluble metals from the literature, and our measured DTT responses for these species, we estimate that for typical fine particle samples approximately 80% of DTT loss is from transition metals (especially copper and manganese), while quinones account for approximately 20%. We find a similar result for DTT loss measured in a small set of PM2.5 samples from the San Joaquin Valley of California. Because of the important contribution from metals, we also tested how the DTT assay is affected by EDTA, a chelator that is sometimes used in the assay. EDTA significantly suppresses the response from both metals and quinones; we therefore recommend that EDTA should not be included in the DTT assay.

scholarly journals On dithiothreitol (DTT) as a measure of oxidative potential for ambient particles: evidence for the importance of soluble transition metals

2012 ◽  
Vol 12 (19) ◽  
pp. 9321-9333 ◽  
Author(s):  
J. G. Charrier ◽  
C. Anastasio
Keyword(s):  
Particulate Matter ◽  
Transition Metals ◽  
Fine Particulate Matter ◽  
Chemical Species ◽  
Past Research ◽  
Active Species ◽  
Oxidative Potential ◽  
Adverse Health Effects ◽  
Redox Active ◽  
Small Set

Abstract. The rate of consumption of dithiothreitol (DTT) is increasingly used to measure the oxidative potential of particulate matter (PM), which has been linked to the adverse health effects of PM. While several quinones are known to be very reactive in the DTT assay, it is unclear what other chemical species might contribute to the loss of DTT in PM extracts. To address this question, we quantify the rate of DTT loss from individual redox-active species that are common in ambient particulate matter. While most past research has indicated that the DTT assay is not sensitive to metals, our results show that seven out of the ten transition metals tested do oxidize DTT, as do three out of the five quinones tested. While metals are less efficient at oxidizing DTT compared to the most reactive quinones, concentrations of soluble transition metals in fine particulate matter are generally much higher than those of quinones. The net result is that metals appear to dominate the DTT response for typical ambient PM2.5 samples. Based on particulate concentrations of quinones and soluble metals from the literature, and our measured DTT responses for these species, we estimate that for typical PM2.5 samples approximately 80% of DTT loss is from transition metals (especially copper and manganese), while quinones account for approximately 20%. We find a similar result for DTT loss measured in a small set of PM2.5 samples from the San Joaquin Valley of California. Because of the important contribution from metals, we also tested how the DTT assay is affected by EDTA, a chelator that is sometimes used in the assay. EDTA significantly suppresses the response from both metals and quinones; we therefore recommend that EDTA should not be included in the DTT assay.

scholarly journals Review of PM Oxidative Potential Measured with Acellular Assays in Urban and Rural Sites across Italy

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 626 ◽  
Author(s):  
Pietrogrande ◽  
Russo ◽  
Zagatti
Keyword(s):  
Rural Areas ◽  
Active Species ◽  
Water Soluble ◽  
Traffic Emissions ◽  
Fuel Oil ◽  
Anthropogenic Sources ◽  
Chemical Components ◽  
Aerosol Formation ◽  
Oxidative Potential ◽  
Redox Active

This work is an overview of the oxidative potential (OP) values up to date measured in Italy, with the aim to provide a picture of the spatial and seasonal variability of OP in the various geographical areas across Italy. The summarized works used the common acellular assays-based dithiothreitol (OPDTT), ascorbic acid (OPAA), glutathione (OPGSH), and 2',7'-dichlorodfluorescein (OPDCFH) assays. The paper describes the association of OP responses with PM chemical composition, the sensitivity of various acellular OP assays to PM components and emission sources, and PM size distribution of the measured OP values. Our synthesis indicates that crustal and transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn, and V), secondary ions and carbonaceous components (elemental carbon, EC, organic carbon, OC and water soluble carbon, WSOC) show significant correlations with OP across different urban and rural areas and size ranges. These chemical species are mainly associated with various PM sources, including residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation. Although the OP assays are sensitive to the same redox-active species, they differ in the association with PM chemical components. The DDT assay is mainly sensitive to the organic compounds that are mostly accumulated in the fine PM fraction, i.e., tracers of burning sources, and redox active organics associated with other markers of photochemical aging. In contrast, OPAA and OPGSH were mostly responsive to metals, mainly those related to non-exhaust traffic emissions (Cu, Zn, Cr, Fe, Ni, Mn, Sn, Cd, Pb), that are mainly accumulated in the coarse PM. Among the investigated sites, our synthesis shows larger OP values in Trentino region and the Po Valley, that may be explained by the high density of anthropogenic sources, and the orographic and meteorological characteristics, that favor the pollutants accumulation and aerosol photo-oxidative aging.

scholarly journals Phosphate Buffer Solubility and Oxidative Potential of Single Metals or Multielement Particles of Welding Fumes

Atmosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 30
Author(s):  
Manuella Ghanem ◽  
Esperanza Perdrix ◽  
Laurent Yves Alleman ◽  
Davy Rousset ◽  
Patrice Coddeville
Keyword(s):  
Transition Metals ◽  
Phosphate Buffer ◽  
Soluble Fraction ◽  
Certified Reference Materials ◽  
Health Effect ◽  
Oxidative Capacity ◽  
Pure Metal ◽  
Welding Fumes ◽  
Oxidative Potential ◽  
Potential Health

To evaluate the chemical behavior and the health impact of welding fumes (WF), a complex and heterogeneous mixture of particulate metal oxides, two certified reference materials (CRMs) were tested: mild steel WF (MSWF-1) and stainless steel WF (SSWF-1). We determined their total chemical composition, their solubility, and their oxidative potential in a phosphate buffer (PB) solution under physiological conditions (pH 7.4 and 37 °C). The oxidative potential (OPDTT) of WF CRMs was evaluated using an acellular method by following the dithiothreitol (DTT) consumption rate (µmol DTT L−1 min−1). Pure metal salts present in the PB soluble fraction of the WF CRMs were tested individually at equivalent molarity to estimate their specific contribution to the total OPDTT. The metal composition of MSWF-1 consisted mainly of Fe, Zn, Mn, and Cu and the SSWF-1 composition consisted mainly of Fe, Mn, Cr, Ni, Cu, and Zn, in diminishing order. The metal PB solubility decreased from Cu (11%) to Fe (approximately 0.2%) for MSWF-1 and from Mn (9%) to Fe (<1%) for SSWF-1. The total OPDTT of SSWF-1 is 2.2 times the OPDTT of MSWF-1 due to the difference in oxidative capacity of soluble transition metals. Cu (II) and Mn (II) are the most sensitive towards DTT while Cr (VI), Fe (III), and Zn (II) are barely reactive, even at higher concentrations. The OPDTT measured for both WF CRMs extracts compare well with simulated extracts containing the main metals at their respective PB-soluble concentrations. The most soluble transition metals in the simulated extract, Mn (II) and Cu (II), were the main contributors to OPDTT in WF CRMs extracts. Mn (II), Cu (II), and Ni (II) might enhance the DTT oxidation by a redox catalytic reaction. However, summing the main individual soluble metal DTT response induces a large overestimation probably linked to modifications in the speciation of various metals when mixed. The complexation of metals with different ligands present in solution and the interaction between metals in the PB-soluble fraction are important phenomena that can influence OPDTT depletion and therefore the potential health effect of inhaled WF.

Computational Study on Compound I Redox-Active Species in Horseradish Peroxydase Enzyme: Conformational Fluctuations and Solvation Effects

2010 ◽  
Vol 114 (20) ◽  
pp. 6817-6824 ◽  
Author(s):  
Costantino Zazza ◽  
Amedeo Palma ◽  
Nico Sanna ◽  
Simone Tatoli ◽  
Massimiliano Aschi
Keyword(s):  
Computational Study ◽  
Active Species ◽  
Compound I ◽  
Solvation Effects ◽  
Redox Active

scholarly journals Biochemical characterization of the purple form of Marinobacter hydrocarbonoclasticus nitrous oxide reductase

2012 ◽  
Vol 367 (1593) ◽  
pp. 1204-1212 ◽  
Author(s):  
Simone Dell'Acqua ◽  
Sofia R. Pauleta ◽  
José J. G. Moura ◽  
Isabel Moura
Keyword(s):  
Nitrous Oxide ◽  
Redox State ◽  
Biochemical Characterization ◽  
Specific Activity ◽  
Active Species ◽  
Nitrous Oxide Reductase ◽  
Strictly Anaerobic ◽  
Prolonged Incubation ◽  
Redox Active ◽  
Marinobacter Hydrocarbonoclasticus

Nitrous oxide reductase (N 2 OR) catalyses the final step of the denitrification pathway—the reduction of nitrous oxide to nitrogen. The catalytic centre (CuZ) is a unique tetranuclear copper centre bridged by inorganic sulphur in a tetrahedron arrangement that can have different oxidation states. Previously, Marinobacter hydrocarbonoclasticus N 2 OR was isolated with the CuZ centre as CuZ*, in the [1Cu 2+ : 3Cu + ] redox state, which is redox inert and requires prolonged incubation under reductive conditions to be activated. In this work, we report, for the first time, the isolation of N 2 OR from M. hydrocarbonoclasticus in the ‘purple’ form, in which the CuZ centre is in the oxidized [2Cu 2+ : 2Cu + ] redox state and is redox active. This form of the enzyme was isolated in the presence of oxygen from a microaerobic culture in the presence of nitrate and also from a strictly anaerobic culture. The purple form of the enzyme was biochemically characterized and was shown to be a redox active species, although it is still catalytically non-competent, as its specific activity is lower than that of the activated fully reduced enzyme and comparable with that of the enzyme with the CuZ centre in either the [1Cu 2+ : 3Cu + ] redox state or in the redox inactive CuZ* state.

Redox chemistry of CeO2 nanoparticles in aquatic systems containing Cr(vi)(aq) and Fe2+ ions

2019 ◽  
Vol 6 (7) ◽  
pp. 2269-2280
Author(s):  
Jessica R. Ray ◽  
Xuanhao Wu ◽  
Chelsea W. Neil ◽  
Haesung Jung ◽  
Zhichao Li ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Redox Chemistry ◽  
Industrial Applications ◽  
Active Species ◽  
Ceo2 Nanoparticles ◽  
Aquatic Systems ◽  
Aquatic Environments ◽  
Catalytic Activities ◽  
Redox Active

CeO2 nanoparticles are extensively used in industrial applications owing to their high redox-catalytic activities and, as a result, may appear in aquatic environments where they undergo significant surface chemistry transformation with other redox-active species.

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