Metal fingerprinting and chemothermal isolation methods to quantify natural and engineered carbon nanoparticles

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CBET - 1336794Overview:The PIs seek to develop methodology to quantify, fingerprint, and distinguish natural and engineeredcarbonaceous nanoparticles using thermal separation techniques and metal content signatures.Building on well-established thermal methods to quantify black carbon (BC) soot, the PIspropose a technique that distinguishes non-nanoparticulate natural organic matter, single-walledcarbon nanotubes (SWCNTs), and BC (the most ubiquitous, natural carbonaceous nanoparticle)based on their distinct thermal stabilities. Preliminary results suggest that natural organicmatter, SWCNTs, and BC have unique oxidation ranges and could be distinguished and quantifiedfollowing sequential oxidations coupled with elemental analysis. Here, we aim to demonstratethat these thermal stabilities are preserved in complex mixtures of air, water, sediments,and soil, and as a result, can be used to quantitatively delineate the nanoparticles (e.g.,natural vs. engineering) in environmental matrices. Furthermore, bulk metal contents determinedvia complete acid digestion and mass spectrometry should provide a route toward source apportionment.Advantages of this approach include the low cost, accessibility, high-throughput capabilities,and minimal sample processing (e.g., extraction) required for this method, which reduces thepotential for analyte loss and transformation during analysis.Intellectual Merit :The National Research Council 2012 EHS Nanotechnology Research Strategy report listed analyticaltechniques as the first research priority. Current approaches for measuring carbonaceousnanoparticles (CNPs) in the work place (and atmosphere) primarily rely on light-scatteringparticle sizers, which provide a bulk measure of nano-sized particles. However, as syntheticapproaches to form engineered carbonaceous nanoparticles (i.e, carbon nanotubes and graphene)are known to co-produce natural nanoparticles (i.e., soot), current results are reportingnatural plus engineered nanoparticle exposure. Thus, it is not possible to quantitativelydetermine occupational exposure to engineered nanoparticles. In addition, there are no methodsto assess release of engineered nanoparticles to the atmosphere, which is a likely vectorfor CNP transport to the environment. This has severe consequences for ongoing nanoparticleresearch: (1) fate models lack validated source data, (2) occupational exposure can be neitherassessed nor enforced, and (3) environmental release can not be mitigated where necessary.Upon project completion, quantitatively differentiation of natural and engineered carbonaceousnanoparticles (NPs) will be possible for the first time, allowing accurate assessment of exposureto engineered NPs, which have unique properties, morphologies, and toxicities compared tonatural NPs. These goals are within the team?s reach and rely on affordable, accessible technologies.Broader Impacts :The PIs and their research groups are actively involved in the outreach efforts hosted bythe Center for the Environmental Implications of Nano-technology (CEINT) at Duke University,as well as other science enrichment activities there, including Females Excelling More inMath Engineering and Science (FEMMES) (100% females from underrepresented groups) volunteerscience workshops. As part of the proposed work, the PIs will establish a nano-analyticalK-12 education module (Is CSI for real? Rapid Nano-forensics?), and this will be taught aspart of NanoDays, FEMMES, and later distributed to the CEINT network of K-12 educators. Additionally,the program will be modified for a more advanced audience (e.g., public library and seniorcenter), delivered live, and videotaped for web distribution.