Abstract

GRUTTER, Michel. Multi-Gas analysis of ambient air using FTIR spectroscopy over Mexico City. Atmósfera [online]. 2003, vol.16, n.1, pp.1-13. ISSN 0187-6236.

A Fourier Transform Infrared [FTIR] spectrometer was used to analyze the composition of ambient air at a specific site in the Mexico City metropolitan area. A continuous flow of air was passed through a multi-pass gas cell and the absorption spectra were collected over a period of two weeks. Quantitative analysis was performed by means of the classical-least square (CLS) method using synthetically generated spectra as references and calibration sources. Ambient levels of CO, CO₂, CH₄ and N₂O are reported with a time resolution of live minutes for September 2001, showing interesting results in their diurnal patterns. Comments on the precision, detection limits and signal-to-noise of the instrument are included for the evaluation of this technique. Water concentrations were estimated and compared with those obtained with a relative-humidity sensor. The technique of extractive FTIR for ambient trace-gas monitoring was utilized in Mexico for the first time and some potential applications are given.

Keywords : FTIR spectroscopy air monitoring; Mexico City.

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