GC-FID or GC-TCD are good choices for light gas analysis by choosing the right column. Chromatgoraphy is a part of separation-based technic. Can we analyse a sample containing many components by IR, UV or spectroscopy ?
At mid-IR spectral range, one can find powerful species specific detection of small HC molecules, if proper spectroscopy is chosen. see HITRAN database.
Mr. Azzouz,
The IR-spectroscopy rather than UV-one can provide meaningful qualitative, quantitative and structural information for hydrocarbons. Please find as an atatchment the characteristic frequencies for saturated-, unsaturated and aromatic derivatives with few shown examples of spectra. even mixtures can de unambiguously determined. Useful refs are also shown.
More information about which electronic transitions can be observed in UV-region, and why you can obtain scarce information for hydrocarbons by this method you may find following the discussion and the atatchments provided:
https://www.researchgate.net/post/What_is_the_interpretation_if_we_get_a_step_like_absorption_in_UV-Visible_Spectroscopy
Thank you very much Pr Zhogshan for your fast replay. I'm a simply user of FTIR (I used usually separation methods). I didn't understand your phrase: if proper spectroscopy is chosen.
Hello Azzouz...
If you have a good spectral database (good = contains IR spectral profiles of all target compounds), a single spectral profile can be deconvoluted, revealing which compounds are present. Usually, modern FT-IR software suites accompanying spectrometers have a deconvolution tool. If your IR setup is equipped with a gas phase transmission cell, I believe you could have favorable results without need to run your samples through GC to separate compounds prior to taking IR spectra.
I have done MID-FTIR spectral deconcolutions using Thermo and Bruker spectrometers software with good results...
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