gas concentration / background gas composition / gas matrix / postacquisition data processing step / background gas effects / post-processing step / background gas / gas mixture / spectral algorithms / gas mole fractions / analyte gas measurement / background gas absorption features / gas components / analyte gas / instrument software / background gas component / background gas mixture / background gas corrections / gas corresponding / linear and stable technology / background gas species / background gas variations / gas species / analyte gas concentration / analyte gas present / background gas matrix / /