EPA/600/R-14/244 | August 2014 | www.epa.gov/research Detection and Characterization of Engineered Nanomaterials in the Environment: Current State-of-the-Art and Future Directions Report, Annotated Bibliography, and Image Library R E S E A R C H A N D D E V E L O P M E N T This page intentionally left blank. Detection and Characterization of Engineered Nanomaterials in the Environment: Current State-of-the-Art and Future Directions Report, Annotated Bibliography, and Image Library Final Report Prepared by: Manuel D. Montaño and James Ranville Colorado School of Mines, Department of Chemistry Gregory V. Lowry Carnegie Mellon University, Department of Civil and Environmental Engineering Julie Blue, Nupur Hiremath, Sandie Koenig, and Mary Ellen Tuccillo The Cadmus Group,Inc. Scientific, Technical, Research, Engineering, and Modeling Support II (STREAMSII) The Cadmus Group,Inc. Contract No. EP-C-11-039 Task Order 5 for Task Order Manager Steven P. Gardner Characterization and Monitoring Branch U.S. Environmental Protection Agency Office of Research and Development National Exposure Research Laboratory Environmental Sciences Division Las Vegas, NV 89119 Although this work was reviewed by EPA and approved for publication, it may not necessarily reflect official Agency policy. Mention of trade names and commercial products does not constitute endorsement or recommendation for use. U.S. Environmental Protection Agency Office of Research and Development Washington, DC 20460 This page intentionally left blank. Disclaimer The United States Environmental Protection Agency through its Office of Research and Development funded and managed the research described here. It has been peer reviewed by the EPA and approved for publication. This page intentionally left blank. Contents 1. INTRODUCTION ...................................................................................................................... 1 Definition and properties of nanoparticles .................................................................................. 2 2. NATURAL COLLOIDS AND NANOPARTICLES ................................................................. 5 Classification and origin of biogenic and geogenic materials .................................................... 6 Composition and interferences of some common natural nanoscale minerals ........................... 6 Estimates of ENP behavior and fate ........................................................................................... 8 NM-facilitated contaminant transport in the subsurface ............................................................. 8 3. REACTIVITY AND PERSISTENCE ....................................................................................... 9 Alterations in Organic Coatings................................................................................................ 10 Loss of coatings .................................................................................................................... 11 Overcoating or Alteration of Coatings .................................................................................. 11 Impact of coating loss or gain on the ability to detect NPs .................................................. 12 Dissolution and Ligation ........................................................................................................... 13 Oxidation and Reduction (Redox) Reactions ........................................................................... 13 Aggregation............................................................................................................................... 14 Biological Transformations ...................................................................................................... 14 4. NANOMETROLOGY ............................................................................................................. 15 A. Review of available analytical methodologies ............................................................... 19 Methods based on separation by size .................................................................................... 19 Ensemble particle detection and characterization methods .................................................. 22 Spectroscopy techniques ....................................................................................................... 24 Particle counting and characterization methods ................................................................... 25 Optical and biological sensors .............................................................................................. 27 B. ENP Characterization in Complex Laboratory Matrices ............................................... 28 Size, morphology, and aggregation state .............................................................................. 28 Surface charge/surface groups .............................................................................................. 29 Dissolved ions vs. nanoparticulates ...................................................................................... 30 C. ENP Detection and Characterization in Environmental Samples .................................. 30 Expected low ENP concentrations ........................................................................................ 31 Elevated natural NP / colloid background ............................................................................ 31 Preserving sample representativeness ................................................................................... 34 5. NEW APPROACHES .............................................................................................................. 34 i Mass spectrometry-based methods ........................................................................................... 35 Element Ratios .......................................................................................................................... 35 Isotope methods ........................................................................................................................ 36 MALDI-TOF-MS and LDI-TOF-MS ....................................................................................... 36 6. SITE-SPECIFIC ENM RELEASE SCENARIOS ................................................................... 37 ENP production site .................................................................................................................. 37 Site of ENP use ......................................................................................................................... 37 Transport accident ..................................................................................................................... 37 Non-point sources ..................................................................................................................... 38 7. SUMMARY ............................................................................................................................. 38 8. REFERENCES ......................................................................................................................... 39 Tables Table 1. Common engineered nanomaterials and typical applications........................................... 2 Table 2. Common methods of synthesis ......................................................................................... 3 Table 3. Common naturally occurring nanomaterials[5, 6, 42, 44] ................................................ 7 Table 4. Analytical approaches: Limitations and needs for ENP analysis ................................... 18 ii Acronyms AF4 Asymmetric Flow Field Flow Fractionation ATR Attenuated total reflectance CCD Charge-coupled device CFUF Cross-flow ultra-filtration CNT Carbon nanotube CPE Cloud point extraction DCS Differential centripetal sedimentation DLS Dynamic light scattering EDS Energy dispersive spectroscopy ENM Engineered nanomaterial ENP Engineered nanoparticle ESEM Environmental SEM FFF Field flow fractionation Fl-FFF Flow FFF FTIR Fourier-transform infrared spectroscopy HDC Hydrodynamic chromatography HS Humic substances ICP-MS Inductively coupled plasma mass spectrometry IR Infrared LCA Life cycle assessment LIBD Laser-induced breakdown detection MALS or MALLS Multi-angle light scattering MAS Magic angle spinning MS Mass spectrometry NIR Near infrared NIRF Near-infrared fluorescence spectroscopy NM Nanomaterial NMR Nuclear magnetic resonance spectroscopy NOM Natural organic matter NP Nanoparticle NTA Nanoparticle tracking analysis PCS Photon correlation spectroscopy PECs Predicted environmental concentrations PEG Polyethylene glycol ppq Parts per quadrillion ppt Parts per trillion ROS Reactive oxygen species SdFFF Sedimentation FFF SEC Size exclusion chromatography SEM Scanning electron microscopy SEIRA Surface enhanced infrared absorbance SLS Static light scattering SPE Solid-phase extraction SP-ICP-MS Single particle ICP-MS iii SPM Suspended particulate matter SWCNT Single-walled carbon nanotube TEM Transmission electron microscopy UV Ultraviolet UV-Vis UV-visible spectroscopy XAS X-ray absorption spectroscopy iv 1. INTRODUCTION Nanotechnology has become a prominent industrial and scientific field. Its global market value is estimated to exceed $1.5 trillion by the year 2015[1-3]. With increasing production and wider applications, engineered nanoparticles (ENPs) are expected to become routinely present in natural ecosystems. Although ENPs will certainly enter the environment through unintentional