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iCONVERT: An Integrated Device for the UV-Assisted Determination of H 2 S via Mid-Infrared Gas Sensors

2015; American Chemical Society; Volume: 87; Issue: 19 Linguagem: Inglês

10.1021/acs.analchem.5b02731

1520-6882

João Flávio da Silveira Petruci, Arnaldo Alves Cardoso, Andreas Wilk, Vjekoslav Kokoric, Boris Mizaikoff,

Analytical Chemistry and Sensors

In this technical note, we describe an integrated device platform for performing in-flow gaseous conversion reactions based on ultraviolet (UV) irradiation. The system combines, using the same footprint, an integrated UV-conversion device (iCONVERT), a preconcentrator unit (iPRECON), and a new generation of mid-infrared (MIR) gas cell simultaneously serving as a photon conduit, i.e., so-called substrate-integrated hollow waveguide (iHWG) optically coupled to a compact Fourier transform-infrared (FT-IR) spectrometer. The iCONVERT is assembled from two blocks of aluminum (dimensions, 75 mm × 50 mm × 40 mm; L × W × D) containing 4 miniaturized UV-lamps (47mm × 6 mm × 47 mm each). For the present study, the iPRECON-iCONVERT-iHWG sensing platform has specifically been tailored to the determination of H2S in gaseous samples. Thereby, the quantitative UV-assisted conversion of the rather weak IR-absorber H2S into the more pronouncedly responding SO2 is used for hydrogen sulfide detection. A linear calibration model was established in the range of 7.5 to 100 ppmv achieving a limit of detection at 1.5 ppmv using 10 min of sample preconcentration (onto Molecular Sieve 5A) at a flow rate of 200 mL min(-1). When compared to a conventional UV-conversion system, the iCONVERT revealed similar performance. Considering the potential for system miniaturization using, e.g., dedicated quantum cascade lasers (QCL) in lieu of the FT-IR spectrometer, the developed sensing platform may be further evolved into a hand-held device.