1. Urban PM2.5 oxidative potential: Importance of chemical species and comparison of two spectrophotometric cell-free assays.
- Author
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Visentin, Marco, Pagnoni, Antonella, Sarti, Elena, and Pietrogrande, Maria Chiara
- Subjects
PARTICULATE matter ,URBAN pollution ,SPECTROPHOTOMETRY ,OXIDATIVE stress ,QUINONE ,URBAN health ,DITHIOTHREITOL - Abstract
Oxidative potential (OP) of particulate matter (PM) − defined as the capacity of PM to oxidize target molecules generating reactive oxygen species (ROS) − has been proposed as a more health relevant metric than PM mass. In this study two cell-free methods were used to assess the OP of PM filters collected at an urban site and to evaluate correlation with PM mass and PM composition. Among the different assays existing, two inexpensive and user-friendly methods were used both based on spectrophotometric measurements of depletion rate of target reagents oxidized by redox-active species present in PM. One assay measures the consumption of dithiothreitol (OP DTT ) and the other the ascorbate (OP AA ). Although both assays respond to the same redox-active species, i.e., quinones and transition metals, no correlations were found between OP DTT and OP AA responses to compounds standard solutions as well as to ambient samples. When expressed in relation to air volume, OP DTT m −3 strongly correlates with PM 2.5 mass whereas no correlation was found for OP AA m −3 with PM 2.5. When expressed on mass basis, both OP DTT μg −1 and OP AA μg −1 show a strong dependence on the sample composition, with higher OP for summer samples. OP DTT m −3 were highly correlated with the determined metals (Cu, Zn, Cr, Fe, Ni, Mn) whereas OP AA m −3 showed only moderate correlation with Cu and Mn. Thus, the two assays could potentially provide complementary information on oxidative potential characteristic of PM. Consequently, the combination of the two approaches can strengthen each other in giving insight into the contribution of chemical composition to oxidative properties of PM, which can subsequently be used to study health effects. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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