Determination of Metal Impurities in Carbon Nanotubes Sampled Using Surface Wipes

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/h2o2 digestion 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. � 2016 mary-luyza avramescu et al.