Continued research on the development and implementation of a high-performance micro analytical system capable of on-site speciated analysis of volatile and semi-volatile organic compounds (VOCs and SVOCs) encountered as complex mixtures at low-/sub-part-per-billion concentrations in non-industrial indoor working environments is proposed. Application to other occupational health monitoring needs will also be addressed. During the first finding cycle of this project, we succeeded in producing and characterizing the performance of a notebook-computer-sized fieldable instrument that employs preconcentration, thermal desorption, high-speed tunable separation, and microsensor-array detection. Detection limits ranging from 0.06 - 17 ppb have been achieved for the components of mixtures of >30 VOCs/SVOCs spanning a 10,000-fold range of vapor pressures captured from l-L air samples. Response patterns combined with chromatographic retention times have been used for vapor identification. Analytical cycle times of < 10 min are possible. Meeting these goals has also led to advances in adsorbent-preconcentrator design, dual-column pressure/temperature-modulated separations using air as carrier gas, and vapor detection, recognition, and quantification with ultra-miniature arrays of polymer-coated surface-acoustic-wave (SAW) microsensors. Here, we propose to field test this first-generation instrument in office buildings and to explore its application for breath analysis and for industrial air monitoring where vapor concentrations tend to be higher. Development of a second-generation microanalytical system with the following refinements/additions is also proposed: a wireless interface to permit unattended operation; an on-board vapor generator for automatic field calibration and system diagnostics; use of an alternative sensor technology with greater sensitivity to reduce sample volumes and/or detection limits; addition of a focusing element to reduce inlet bandwidths and use of alternative separation strategies to improve chromatographic resolution/versatility and reduce analysis time; and implementation of Si-micromachined components to reduce size and power. Laboratory and field testing of this second-generation instrument will then be performed. This system represents a significant advancement over the current state-of-the-art in monitoring instrumentation for complex vapor mixtures, obviating the need for conventional sorbent-tube/GC-MS methods for routine indoor air (and other) monitoring. The versatility of this instrument will facilitate the assessment of exposure distributions and the implementation of rational intervention strategies related to indoor air quality and other occupational health problems.
|Zhong, Qiongyan; Steinecker, William H; Zellers, Edward T (2009) Characterization of a high-performance portable GC with a chemiresistor array detector. Analyst 134:283-93|