universal detector

[woow]

I want to know the advantages/disadvantages, purpose, and differences of the application of a universal detector.

Thanks,
Winnie

[tom jupille]

There are several "universal" detectors. To which one are you referring?

[woow]

a short description of LC detectors like RI and ELSD vs UV/Diode Array.

[woow]

I can probably look at the book you suggested, but I would like to personally ask as well.

Thanks
WW

[tom jupille]

If your analyte(s) have a significant chromophore in the UV (molar extinction coefficient > 10^2 or so), UV at an appropriate wavelength will be a better choice (more sensitive; fewer interferences).

If no chromophore, then RI or ELSD will be required. They are, however, more prone to interferences ("universal" means they respond to everything, whether you are interested in it or not).

If you are dealing with proteins, there are almost always enough aromatic residues to make UV detection at 280 nm feasible.

I hate to sound like a broken record, but there is a more detailed comparison of detector options in the Basic HPLC and CE of Biomolecules book ( http://tinyurl.com/n4knp ) I recommended in the thread on insulin ( http://www.sepsci.com/chromforum/viewtopic.php?t=4729 )

[woow]

That is cool.

I guess I have some good reading tonight.

Thanks again
WW

[Alfred88]

Dear 'woow':

Did you mean 'universal' as "commonly used in most LC separations, and available from many HPLC vendors" or 'universal' as "used for most (or all) species in LC separations, but is available from one vendor"?

In the former case, there are some detectors on the market: UV-Vis, RI, or ELSD.

In the latter case, there is only one: The Corona-charged Aerosol detector, available from ESA Analytical (www.esainc.com). The selling points: more sensitive than RI and UV detectors; can be used for isocratic and gradient (RI does not work for gradient); not limited by the presence of chromophores.
(We currently do not have this detector, but I am planning to put together a proposal to acquire it next year).

Alfred.

[woow]

what I am looking for if anybody seen, approach, or favor the advantages of using RI, UV, ELSD, MS, etc. in analysis of say proteins and where am I limited by using any of the detection systems.

Thanks,
Winnie