Effective assessment of nanoparticle exposures requires accurate characterization of the aerosol. Of increasing concern is personal exposure to engineered nanoparticles that are specifically designed for use in the nanotechnology sector. This manuscript describes the operation and use of a personal sampler that utilizes thermophoretic force to collect nanoparticles onto a standard TEM (transmission electron microscope) grid. After collection, nanoparticles on the TEM grid are analyzed with an electron microscope, and the resultant data used to determine the characteristics of the nanoparticle aerosol sampled. Laboratory experiments were conducted to determine the inlet losses and collection efficiency of the thermophoretic sampler for particles between 20 and 600 nm in diameter. These results are used together with theory for thermophoretic velocity to form a transfer function that relates the properties of the collected particles to the properties of the sampled aerosol. The transfer function utilizes a normalization factor, F(d), which is larger than unity for very small particles but approaches unity for particles larger than about 70 nm.

A low-cost electrochemical sensor with Nafion/Bi modification using adsorptive stripping voltammetry for Co and Ni determination in airborne particulate matter and welding fume samples is described. Carbon stencil-printed electrodes (CSPEs) manufactured on low-cost PET films were utilized. Dimethylglyoxime (DMG) was used as a Co(II) and Ni(II) chelator with selective chemical precipitation for trace electrochemical analysis. Electrochemical studies of the Nafion/Bi-modified CSPE indicated a diffusion-controlled redox reaction for Co and Ni measurements. The Nafion coating decreased the background current and enhanced the measured peak current. Repeatability tests based on changes in percent relative standard deviation (RSD) of peak current showed the electrode could be used at least 15 times before the RSD exceeded 15% (the reported value of acceptable repeatability from Association of Official Analytical Chemists (AOAC)) due to deterioration of electrode surface. Limits of detection were 1 μg L−1 and 5 μg L−1 for Co and Ni, respectively, which were comparable to electrochemical sensors requiring more complicated modification procedures. The sensor produced a working range of 1–250 and 5–175 μg L−1 for Co and Ni, respectively. Interference studies showed no other metal species interfered with Co and Ni measurements using the optimized conditions. Finally, the developed sensors were applied for Co and Ni determination in aerosol samples generated from Co rods and a certified welding-fume reference material, respectively. Validation with ICP-MS showed no statistically different results with 95% confidence between sensor and the ICP methods.

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