The broad goal of this project is to develop and characterize a wearable gas chromatographic microanalytical system (mGC) for near-real-time recognition and quantification of the components of complex mixtures of volatile organic compounds (VOC) encountered in working environments. The proposed mGC, referred to as a Personal Exposure Monitoring Microsystem (PEMM), will be battery operated, autonomous, and small/light-weight enough to mount on the belt of a worker, yet capable of simultaneous personal exposure measurements of at least 10-15 user-selectable VOCs every 10-15 minutes in a complex matrix of background VOCs. The performance of the PEMM mGC will rely on an ensemble of Si-microfabricated devices for selective sampling/preconcentration; focused injection; temperature-programmed, dual-column chromatographic separation; and 'spectral detection' with a microsensor array. These will be combined with a commercial mini-pump, possibly a small on-board He gas supply, mini-valves, interface circuitry, an embedded microcontroller for operating the instrument and storing exposure data, and a wireless link for on-the-fly downloading of data to a smartphone or remote host computer. Post-shift analysis of the chromatographically resolved array response patterns for each mixture component will permit construction of detailed time-exposure profiles for comparison with occupational exposure limits or classification of exposure frequencies and intensities for epidemiologic studies. Innovative designs and strategies for selective preconcentration, high-resolution/high-speed separation, and microsensor-based detection with chemometric peak deconvolution will be implemented in the PEMM, and operating conditions will be adjustable to permit accurate measurements of VOC concentrations over a ~50-fold range for any compound, spanning from 0.1-5 times the recommended exposure limits. Detection limits as low as 0.05 ppm will be achievable. The capability of this instrument for assessing human exposures to VOCs will be demonstrated through a series of mock-field tests using target and background VOC mixtures of varying complexity in task-exposure scenarios representative of jobs in NORA-defined construction, manufacturing, health care, and other sectors. The successful project will yield a tool with unprecedented capabilities for measuring worker exposures to VOCs, in terms of temporal resolution, the number of specific analytes, and the cost per measurement. This will address stated needs/goals primarily in NIOSH cross-sector programs in Exposure Assessment and Emergency Preparedness and Response. By including a start-up company on our team with expressed interest in commercializing this technology, we will facilitate its transfer to the private sector (and user community), consistent with NIOSHs Research-to-Practice initiative.
The lack of adequate exposure data has been consistently cited as the most critical factor limiting efforts to define exposure-response relationships in epidemiologic studies of disease in worker populations; particularly where complex mixtures are involved. This; in turn; impedes efforts to establish meaningful workplace exposure limits and to determine compliance with such limits once established. The successful project will fill the need for small; inexpensive; wearable; turn-key instrumentation capable of direct; autonomous identification and quantification of multiple user-selectable VOCs in complex workplace-air mixtures with high temporal resolution.
| Bryant-Genevier, Jonathan; Zellers, Edward T (2015) Toward a microfabricated preconcentrator-focuser for a wearable micro-scale gas chromatograph. J Chromatogr A 1422:299-309 |
