title: Extraction and quantification of carbon nanotubes in biological matrices with application to rat lung tissue.
abstract: Extraction of carbon nanotubes (CNTs) from biological matrices such as rat lung tissue is integral to developing a quantification method for evaluating the environmental and human health exposure and toxicity of CNTs. The ability of various chemical treatment methods, including Solvable (2.5% sodium hydroxide/surfactant mixture), ammonium hydroxide, nitric acid, sulfuric acid, hydrochloric acid, hydrofluoric acid, hydrogen peroxide, and proteinase K, to extract CNTs from rat lung tissue was evaluated. CNTs were quantified using programmed thermal analysis (PTA). Two CNTs were used to represent the lower (500 °C) and upper (800 °C) PTA limit of CNT thermal stability. The recovery efficiency of each of the eight chemical reagents evaluated was found to depend on the ability to (1) minimize oxidation of CNTs, (2) remove interfering background carbon from the rat lung tissue, and (3) separate the solid-phase CNTs from the liquid-phase dissolved tissue via centrifugation. A two-step extraction method using Solvable and proteinase K emerged as the optimal approach, enabling a recovery of 98 ± 15% of a 2.9 ± 0.19 μg CNT loading that was spiked into whole rat lungs. Due to its high yield and applicability to low organ burdens of nanomaterials, this extraction method is particularly well suited for in vivo studies to quantify clearance rates and retained CNTs in lungs and other organs.
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University , Tempe, Arizona 85287-5306, United States.
authors.forename: Kyle
authors.initials: K
authors.lastname: Doudrick
authors.forename: Nancy
authors.initials: N
authors.lastname: Corson
authors.forename: Günter
authors.initials: G
authors.lastname: Oberdörster
authors.forename: Alison C
authors.initials: AC
authors.lastname: Elder
authors.forename: Pierre
authors.initials: P
authors.lastname: Herckes
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
authors.forename: Paul
authors.initials: P
authors.lastname: Westerhoff
mesh_terms: D000818:Animals; D008168:Lung / Q000378:metabolism*; D037742:Nanotubes, Carbon; D051381:Rats; D013059:Spectrum Analysis, Raman
chemical_list: D037742:Nanotubes, Carbon