title: Determination of Metal Impurities in Carbon Nanotubes Sampled Using Surface Wipes.
abstract: Residual metal impurities in carbon nanotubes (CNTs) provide a means to distinguish CNT from non-CNT sources of elemental carbon in environmental samples. A practical and cost-effective analytical approach is needed to support routine surface monitoring of CNT metal tracers using wipe sampling. Wipe sampling for CNT metal tracers is considered a qualitative indicator of the presence of CNTs, not a quantitative exposure metric. In this study, two digestion approaches (microwave-assisted nitric acid/H2O2digestion and ultrasonic nitric/HF acid digestion) in conjunction with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) determination were evaluated for their ability to extract metal impurities from CNT particles captured on wipe substrates. Aliquots of different carbon nanotubes (including NIST 2483 single-wall CNT) with and without GhostWipes™ (ASTM E-1792 compliant) were used to compare the performance of the digestion methods. The microwave digestion method accommodated the bulky wipe sample and also eliminated potential ICP-MS signal interferences related to incomplete digestion. Although quantitative recoveries requiring lengthy multistep digestion protocols may be necessary in other applications, the near-total recoveries achieved in the present study for CNT catalyst elements were adequate for identifying surface contamination of CNTs in the workplace using wipe sampling.
authors.affiliation: Environmental Health Science and Research Bureau, HECSB, Health Canada, 50 Columbine Driveway, Tunney's Pasture 0803C, Ottawa, ON, Canada K1A 0K9.
authors.forename: Mary-Luyza
authors.initials: ML
authors.lastname: Avramescu
authors.affiliation: Environmental Health Science and Research Bureau, HECSB, Health Canada, 50 Columbine Driveway, Tunney's Pasture 0803C, Ottawa, ON, Canada K1A 0K9; Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, ON, Canada K1N 6N5.
authors.forename: Pat E
authors.identifier: 0000-0001-6748-4255
authors.initials: PE
authors.lastname: Rasmussen
authors.affiliation: Environmental Health Science and Research Bureau, HECSB, Health Canada, 50 Columbine Driveway, Tunney's Pasture 0803C, Ottawa, ON, Canada K1A 0K9.
authors.forename: Marc
authors.initials: M
authors.lastname: Chénier