Zebra GC: A mini gas chromatography system for trace-level determination of hazardous air pollutants

A ready-to-deploy implementation of a microfabricated gas chromatography (μGC) system characterized for detecting hazardous air pollutants (HAPs) at parts-per-billion (ppb) concentrations in complex mixtures has been described. A microfabricated preconcentrator (μPC), MEMS separation column with on-chip thermal conductivity detector (μSC-TCD), flow controller unit, and all necessary flow and thermal management as well as user interface circuitry are integrated to realize a fully functional μGC system. The work reports extensive characterization of μPC and μSC-TCD for target analytes: benzene, toluene, tetrachloroethylene, chlorobenzene, ethylbenzene, and p-xylene. A Limit of Detection (LOD) of ∼1 ng was achieved, which corresponds to a sampling time of 10 min at a flow rate of 1 mL/min for an analyte present at ∼25 ppbv. An innovative method using flow-manipulation generated sharp injection plugs from the μPC even in the presence of a flow-sensitive detector like a μTCD. The μGC system is compared against conventional automated thermal desorption-gas chromatography-flame ionization detector (ATD-GC-FID) system for real gasoline samples in simulated car refueling scenario. The μGC system detected five peaks, including three of the target analytes and required ∼3 orders of magnitude lower sample volume as compared to the conventional system.