Low-Cost Analytical Tools for Particulate Matter Composition Analysis
Research seminar abstract
Particulate matter (PM) represents a major health problem, contributing to 4 million deaths annually as reported by the Global Burden of Disease (GBD) study (http://www.healthdata.org). PM toxicity is linked to its chemical composition. The toxic chemical components of PM include trace metals, reactive oxygen species, and organic compounds that cause DNA oxidative damage and carcinogenesis in the respiratory and cardiovascular systems. I will present two efforts towards developing low-cost, portable, and disposable analytical devices for chemical characterization of PM. First, a simple electrochemical device for analyzing trace metals including Zn, Cd, Pb, Co, and Ni in PM will be presented. The device was fabricated using stencil-printing on a low-cost polyethylene transparency (PET) sheet to create carbon stencil-printed electrode (CSPE). For Zn, Cd, and Pb detection, to enhance electrode performance, electrospray deposition of silver nanoparticles (AgNPs) was chosen for electrode modification. An enhanced dispersion of AgNPs on the electrode surface was observed resulting in increase of surface area and better electrochemical performance. In addition, Bi and Nafion were used as co-modifiers to enhance peak current. Finally, acetate buffer (pH 5.0) was found to be suitable to obtain the best limit of detection (LOD) and longest linear operating range. The AgNP/Bi/Nafion-modified CSPE provided LODs of 5.0, 0.5, and 0.1 μg L-1 for Zn, Cd, and Pb detection, respectively. The proposed method was used to measure Zn, Cd, and Pb in PM samples collected with wearable personal air samplers in Fresno, Califonia. The results showed a few samples contained Zn ranging from 0.04-1.41 ng m-3 and one sample contained 0.2 ng m-3 Pb. The results from the proposed method were not significantly different from the results measured using ICP-MS (at 95% confidence). Besides the method developed for Zn, Cd, and Pb detection, CSPEs were also used for Co and Ni analysis because these metals can produce reactive oxygen species via Fenton-like reactions. The CSPE for Co and Ni determination was modified with Bi to improve signal. Furthermore, dimethylglyoxime (DMG) was used as a Co(II) and Ni(II) chelator with highly selective chemical precipitation for adsorptive stripping voltammetry. The approach gave LOD of 1.0 and 5.0 μg L-1 for Co and Ni, respectively. Finally, Bi-modified CSPEs were used to determine Co and Ni in aerosol samples. The amount of Co and Ni in the samples determined using the proposed method was not significantly different from the results obtained using ICP-MS at 95% confidence. In addition to metals, organic compounds are prevalent in PM but their analysis is normally restricted to complicated separation methods. To address this need, the last part of this talk will focus on developing a low-cost, high resolution paper-based electrophoresis device for analysis of organic species in PM samples. Colorimetry and fluorescence were used as the detection methods. Method viability was first established using chlorophenol red and indigo carmine dyes. The parameters affecting the separation included paper type, channel width, and applied potential. Addition of an injection valve into the device improved resolution and reduced peak broadening. For fluorescence detection, the separation of fluorescein isothiocyanate (FITC) and glutamic acid labeled with FITC was used to demonstrate fluorescence detection. In conclusion, the low-cost methods for PM analysis were proposed with using CSPE to detect Zn, Cd, Pb, Ni and Co and using electrophoresis separation on mPAD prepared for effective complicated compounds analysis in the future.
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Speaker: Jaruwan Mettakoonpitak
Speaker Institution: Colorado State University
Event Date: 03-29-2017
Event Time: 4:00 PM
Event Location: Chemistry A101
Mixer Time: 3:45 PM
Mixer Location: Chemistry B101E
Host: C. Henry