Potential for misidentification of environmentally persistent free radicals as molecular pollutants in particulate matter.
Environmentally persistent free radicals (EPFRs) have been shown to form on the surfaces of various types of transition metal-containing particulate matter (PM), and it has been demonstrated they are capable of initiating adverse health impacts. Following sonification and solvent extraction for chemical analysis, they are partially converted to molecular species. Alcoholic solvents extracted the EPFRs with near 100% efficiency, while nonpolar hydrocarbon solvents exhibited <20% efficiency and dichloromethane exhibited 20-55% efficiency. The extracted radicals reacted in solution to form multiple molecular reaction products including catechol, hydroquinone, phenol, chlorinated phenols, dibenzo-p-dioxin, and dibenzofuran. This suggests that EPFRs in environmental samples are indistinguishable from molecular pollutants and are subject to misidentification as molecular adsorbates when traditional extraction and chemical analysis methods are employed. On the basis of these findings, the origin of the toxicity of particulate matter contaminated with toxic organic compounds should be considered for re-evaluation to include the possibility that EPFRs may be a significant contributor, and the impact of some molecular pollutants may have been overestimated.
Truong
Hieu
H
413 Choppin Hall, Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70820, USA.
Lomnicki
Slawo
S
Dellinger
Barry
B
D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D002396:Catechols / Q000032:analysis / Q000737:chemistry; D005591:Chemical Fractionation; D017606:Chlorine Compounds / Q000032:analysis / Q000737:chemistry; D005609:Free Radicals / Q000032:analysis* / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D006873:Hydroquinones / Q000032:analysis / Q000737:chemistry; D052638:Particulate Matter / Q000032:analysis* / Q000737:chemistry; D019800:Phenol / Q000032:analysis / Q000737:chemistry
D000393:Air Pollutants; D002396:Catechols; D017606:Chlorine Compounds; D005609:Free Radicals; D006873:Hydroquinones; D052638:Particulate Matter; D019800:Phenol; C034221:catechol; C031927:hydroquinone