Contribution of Water-Soluble and Insoluble Components and Their Hydrophobic/Hydrophilic Subfractions to the Reactive Oxygen Species-Generating Potential of Fine Ambient Aerosols

Citations Over TimeTop 1% of 2012 papers

Abstract

Relative contributions of water- and methanol-soluble compounds and their hydrophobic/hydrophilic subfractions to the ROS (reactive oxygen species)-generating potential of ambient fine aerosols (D(p) < 2.5 μm) are assessed. ROS-generating (or oxidative) potential of the particulate matter (PM) was measured by the dithiothreitol (DTT) assay. Particles were collected on quartz filters (N = 8) at an urban site near central Atlanta during January-February 2012 using a PM(2.5) high-volume sampler. Filter punches were extracted separately in both water and methanol. Hydrophobic and hydrophilic fractions were then subsequently segregated via a C-18 solid phase extraction column. The DTT assay response was significantly higher for the methanol extract, and for both extracts a substantial fraction of PM oxidative potential was associated with the hydrophobic compounds as evident from a substantial attenuation in DTT response after passing PM extracts through the C-18 column (64% for water and 83% for methanol extract; both median values). The DTT activities of water and methanol extracts were correlated with the water-soluble (R = 0.86) and water-insoluble organic carbon (R = 0.94) contents of the PM, respectively. Brown carbon (BrC), which predominantly represents the hydrophobic organic fraction (referred to as humic-like substances, HULIS), was also correlated with DTT activity in both the water (R = 0.78) and methanol extracts (R = 0.83). Oxidative potential was not correlated with any metals measured in the extracts. These findings suggest that the hydrophobic components of both water-soluble and insoluble organic aerosols substantially contribute to the oxidative properties of ambient PM. Further investigation of these hydrophobic organic compounds could help identify sources of a significant fraction of ambient aerosol toxicity.

Related Papers

• → Kinetics of inhibition of aminoacylase activity by dithiothreitol or 2‐mercaptoethanol(1996)16 cited
• → Differences in organizational structure of insulin receptor on rat adipocyte and liver plasma membranes: role of disulfide bonds.(1980)71 cited
• → Regulation of protein synthesis by hemin Effect of dithiothreitol on the formation and activity of the hemin-controlled translational repressor(1978)19 cited
• → Evidence for distinguishable sites of attack in the reactions of 5′-p-fluorosulfonylbenzoyl adenosine and 5′-p-fluorosulfonylbenzoyl guanosine with rabbit muscle pyruvate kinase(1982)5 cited
• → Reduction of Chymotrypsin A_α by Dithiothreitol(1971)4 cited