Chemical Forums

Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: 10097562 on September 21, 2011, 10:54:37 AM

Title: ultra violet region
Post by: 10097562 on September 21, 2011, 10:54:37 AM

hello everyone, i have a question if anyone can help please. is it possible to analyze for a substance which itself does not absorb in the ultraviolet region? its a written question i have to answer  :(

Title: Re: ultra violet region
Post by: sjb on September 21, 2011, 11:28:37 AM

Quote from: 10097562 on September 21, 2011, 10:54:37 AM

hello everyone, i have a question if anyone can help please. is it possible to analyze for a substance which itself does not absorb in the ultraviolet region? its a written question i have to answer  :(

What does the question actually say? It is, of course, possible to analyse e.g. ethanol by means other than UV, but ethanol itself is not UV active, but I am not sure if that's what you're after here.

Title: Re: ultra violet region
Post by: fledarmus on September 21, 2011, 01:05:26 PM

I'm not sure of what you're asking either. It is possible to react your substance of interest with something that is UV active and analyze for that, or react it with something else that isn't UV active but forms a compound which is and analyze for that, or complex it with a UV indicator and analyze for the indicator. It is also possible that the molecule may be fluorescent and absorb energy that is not in the UV region but emit energy that is.

Title: Re: ultra violet region
Post by: JGK on September 21, 2011, 03:10:09 PM

In chromatogaphy there are a number of detection systems that were designed for the analysis and quantification of componds without chromophores

HPLC:
Evaporative Light Scattering Detector
Charged Aerosol Detector
Refractive Index detector
Mass spectrometry detection

Also most gas chromatoraphy detectors dont require the molecule to have a chromophore