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