A Miniaturized GC with MEMS-Enabled Selective Preconcentration for Monitoring Exp

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DESCRIPTION (provided by applicant): This research proposal is aimed at developing a miniaturized gas chromatography system with selective adsorption capability to identify air hazardous pollutants (HAPs) found in transportation-related and other workplaces. Exposure to HAPs has been linked to a variety of health effects, such as cancer, asthma, autism, reduced fertility, and lower intelligence. Development of effective strategies for reducing occupational exposure to HAPs requires accurate, time-resolved measurement of exposure, but doing so is restricted by the unavailability of compact, lightweight, inexpensive portable analytical instruments. Current practice typically requires collection of a sample in the field using a canister or sorbent tube, transport to the lab, and then application of gas chromatography with a detector to identify and quantify the species present in the environment. This proposal addresses the need for lower cost, compact exposure monitors by merging microelectromechanical systems (MEMS) technology, microelectronics, and analytical chemistry to develop a portable GC system containing a dual-preconcentrator stage for selective adsorption of analytes, separation column with embedded thermal conductivity detector (TCD), and a microprocessor-based controller. The overall iPad-size system will have a concentration factor > 10,000, separation efficiency > 10,000 plates, an overall detection limit < 1ppb, and the ability of selective trapping of analytes of interest enabling a complete GC run from sample collection to detection in less than 10 min. The specific aims of the research described in this proposal are as follows: 1) to design, develop, and evaluate the ¿GC system for measuring exposure to HAPs and 2) to evaluate the system functionality for on-field HAP monitoring through comparison with conventional techniques. Aim 1 is focused on fabricating the preconcentrator with on-chip thermal desorption capability, implementing the dual-preconcentration scheme for selective adsorption, fabricating the column with on-chip TCD and oven, and designing and implementing the brain of the system (electronics) and the required system platform. Through laboratory testing, the MEMS components will be evaluated in terms of concentration and separation characteristics to enable the identification of key compounds in three classes of HAPs: aromatic solvents; polycyclic aromatic hydrocarbons, and non-aromatic hydrocarbons. In Aim 2, the system effectiveness at detecting and quantifying the HAPs of interest will be evaluated in controlled, paired- sample testing to compare results with those obtained by conventional methods using active sampling through a sorbent tube followed by thermal desorption and gas chromatography. We will deploy both the ¿GC system and sorbent tube coupled with a pump at two transportation-related workplaces: a municipal airport (Virginia Tech Montgomery Executive Airport) and bus maintenance facility (Blacksburg Transit). While focused on exposure monitoring, the scientific and technological impacts of this project may extend to other applications if this exploratory research is accomplished successfully. PUBLIC HEALTH RELEVANCE: The goal of the project is to develop a smart portable gas analyzer that can be used to measure hazardous air pollutants in (near) real-time in transportation-related and other workplaces. It can replace cumbersome sampling methods that must be followed by costly analysis in a laboratory. This programmable system is small enough that it can easily be worn to provide a measure of personal exposure to hazardous air pollutants.