RESUMO
This conference report describes the training activities that took place in the frame of the Integrated in Situ Chemical MApping probe (SCHeMA) summer school organized from the 14th to the 16th of June 2016 in Bilbao (Spain).
Assuntos
Ecologia/educação , Monitoramento Ambiental/métodos , Técnicas Biossensoriais/métodos , Ciclo do Carbono , Metais/análise , Compostos Orgânicos Voláteis/análiseRESUMO
The development of a hollow core waveguide (HWG) gas sensor in combination with a fast and compact near-infrared (NIR) spectrometer is presented. The spectrometer operates in the spectral range of 1200-1400 nm and may thus be applied for the detection of gas-phase analytes providing NIR absorptions in that spectral window such as, e.g., methane. Since mid-infrared spectroscopy in combination with HWGs has already been successfully demonstrated for probing hydrocarbons in the gas phase, the present study investigates the achievable sensitivity in the NIR spectral regime. Methane has been selected as an exemplary analyte due to the fact that it shows strong absorption features in the mid-infrared (mid-IR) fingerprint area, but also overtone bands in the NIR. Since the HWG simultaneously serves as a miniaturized absorption gas cell and as an optical waveguide for NIR radiation, a compact yet optical and cost-efficient sensor device was established providing an interesting alternative in target sensing for mid-IR devices. The achieved limit of detection (LOD) was 5.7% (vol./vol.) methane for a 9.5 cm long HWG, 1.6% (vol./vol.) methane for a 39.1 cm long HWG, and 1.3% (vol./vol.) methane for a setup using a 77.4 cm long HWG, which provides the most practical HWG dimensions among the three investigated setups. Limit of quantitation (LOQ) values were calculated at 20.1% (vol./vol.) methane, 8.7% (vol./vol.) methane, and 5.6% (vol./vol.) methane, respectively.