AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Near Real-time Measurement of Carbonaceous Aerosols Using Microplasma Spectroscopy: Application to Measurement of Carbon Nanomaterials
LINA ZHENG, Pramod Kulkarni, M. Eileen Birch, Gregory Deye, Dionysios Dionysiou, Centers for Disease Control and Prevention, NIOSH
Abstract Number: 539 Working Group: Instrumentation and Methods
Abstract We extend the application of our aerosol spark emission spectroscopy system (J. Anal. At. Spectrom., 2012, 27, 1101) to measurement of engineered carbon nanomaterials. The system incorporates coaxial electrodes that preconcentrate the incoming aerosol particles for subsequent analysis using spark emission spectroscopy in near real-time. Preconcentration is accomplished through focused electrostatic deposition of charged aerosol particles onto the tip of a cathode. Following deposition, a pulsed high voltage is applied, forming a pulsed spark discharge (plasma) with energy ranging from 50-300 mJ/pulse. The particulate matter collected on the cathode tip is ablated, atomized and electronically excited by the spark plasma, resulting in atomic emissions that are subsequently recorded using a broadband optical spectrometer for element identification and quantification. The total particulate carbon determined is a good surrogate measure of carbon nanomaterials when particulate organic carbon (OC) and elemental carbon (EC) from other sources are absent or minimal, or correction for the bias can be made. The system was calibrated and detection limit were determined for total carbon using carbon emission at 247.85 nm (C I) and carbonaceous test aerosols. To improve the selectivity for carbon nanomaterials, the cathode was heated to minimize the contribution of condensed OC. The detection limit for total carbon, measurement selectivity, results compared with EC obtained by NIOSH Method 5040, and application to near real-time measurement of single- and multi-walled carbon nanotubes will be presented and discussed.