Gas Chromatographic Microsystems: Development and Application to Problems in Homeland Security and Environmental Health.

Gas Chromatography;Air Monitoring;Explosive Analysis;MEMS;Public Health;Health Sciences;Environmental Health Sciences

Serrano, GustavoKurdak, Cagliyan ;

University of Michigan

关键词: Gas Chromatography;    Air Monitoring;    Explosive Analysis;    MEMS;    Public Health;    Health Sciences;    Environmental Health Sciences;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/98027/gserrano_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This dissertation describes the development and characterization of microanalytical systems for trace-level determinations of airborne volatile and semi-volatile organic compounds. A primary emphasis is placed on a fully integrated, field-deployable, Si-microfabricated gas chromatographic system (μGC) designed for homeland security applications; specifically for fast determinations of the following marker compounds of the explosive trinitrotoluene: 2,4-dinitrotoluene (2,4-DNT), and 2,3-dimethyl-2,3-dinitrobutane (DMNB). The μGC, dubbed INTREPID II, was designed to preconcentrate, inject, separate, and detect/recognize the explosive markers at sub-parts-per-billion concentrations in a short time. The key components are a preconcentrator/focuser (PCF) module that consists of a high-volume sampler (not microfabricated) and a micro-focuser, a wall-coated 1-m-long (1×1 cm) micro-column, and a chemiresistor (CR) array detector that uses monolayer-protected gold nanoparticle (MPN) interface layers. A laboratory prototype, dubbed INTREPID I, was used to determine the initial design and operating conditions of INTREPID II. The PFC module was characterized with a focus on the tradeoffs in performance associated with fast sampling of the explosives markers, including thermal and fluidic operating variables. The determination of the two explosive markers and a 22-component mixture of common indoor air contaminants and alkanes with similar volatilities as the explosive markers in a total analytical cycle time of 2 min was achieved with INTREPID II. The limits of detection (LOD) of the microanalytical system were 0.3 ppb and 0.12 ppb for DMNB AND 2,4-DNT, respectively for a 1-L air sample. Unique sensor-array response patterns for the explosive markers were demonstrated. In a separate project, a comprehensive two-dimensional gas chromatographic subsystem (GC×GC) that uses a microfabricated mid-point thermal modulator (μTM) was assembled and characterized. The influence of several design and operating parameters on performance were examined. A 21-component GC×GC separation was achieved in < 3 min with the optimized subsystem. The performance of this low-power, consumable-free μTM rivals that achievable with many commercial macroscale thermal modulators, suitable for field operation. This body of work has demonstrated the feasibility and advantages of Si-microfabricated analytical systems for next generation portable direct reading instrumentation for selective, trace-level, multi-VOC determinations relevant to homeland security and environmental health applications.