Hi,
I know this is a LC group, but its related to LC-PDA, so I will post it here

On our company there was a guy that said that he could predict the chemical structure of a component when he has seen the UV spectrum from the PDA detector.

He also told that he couldn't predict the whole structure, but only functional groups or typical structures like 3 benzene rings, ...

Is this really possible?
If so, where can I find some references?


Regards

Various chromophores give various UV maximums, interaction between functional groups and thier effect on UV absorbtion is understood so any good textbook should give you that kind of information (Spectrometric Identification of Organic Coumpounds by Silverstein, Bassler and Morrill is the one I have). I would think that the prediction of a structure would be tricky but quite possible.

Hi Anon-09:27

1 - The PDA detector can improve the structure identification process. It is a powerfull tool!!But the number of informations may be more small. You should read the Structure Determination of Organic Compounds of Drs Pretsch, Buhlmann and Affolter. There are the Spectrophotometric Identification of Organic Compouns by Silverstein, too (as were proposed by Anon-10:36).

2 - If you know the molecular structure (the chromophors) it is possible to predict the UV-absorption of any compound.

3 - Are you working with correlated substances?


Good luck

Your colleague's bravado is amusing but the claims made are implausible. There are too few structural details in UV spectra and too many compounds have spectra with similar features to have much hope of doing this if the compounds are true unknowns. Maybe with a limited enough universe of compounds it might be possible but as a general statement this is not very believable.

If the claim were made in conjunction with infrared, NMR or MS I would believe it but not UV.

If you have no information, whatever, for a substance given to you for analysis, it could well be that you can not even identify it, even if you obtained all the spectra of the mentioned methods. On the other hand, each one of these methods might be necessary to remove a question mark. There are usually problems in books of the type mentioned by 2nd anon and Carlos, they are a good starting point to give you a feel for the complexity of this matter.
Though I come from the physical organic chem corner, it has become quite apparent that analytical chemistry is sort of a grand daddy of all of chemistry. The sundry regulations just obliterate this.

Are there online references available?

Just typed "spectral interpretation" into google, got lots of stuff, not simple to decide....., interesting article:
www.suite101.com/article.cmf/6121/35768

HM Mueller,

that link doesn't work with me, no acces to the requested page.


Even if I type "spectral interpretation" into google, I can't find it.

I have worked a few years on natural products structure elucidation. Prediction of a chemical structure just from the UV spectrum is impossible. One might see characteristic absorptions for chromophors. Online or printed references are not especially helpfull, as UV-spectra change depending on solvents used and pH.
If there is some information on the structure (i.e. metabolites that are derived from a known structure) UV spectra can give some hints. LC-MS will give additional information. Major organic chemistry journals require for new strucures usually CNMR and HNMR data, and high resolution MS (or MS and elementary composition). That would be necessary for prove of new structures.

Canīt get into link anymore either, will look at it later when there is more time. Anyway, you can get more specific info from other pages listed by google.