Chiral Detection

[adam]

There have been a few threads recently about chiral chromatography. But I'm wondering - what about chiral detection. Might that be an easier way to go. It seems Jasco specializes in these systems including: Circular dichroism, polarimetry, and ORD.

So I guess I have two questions. First is Jasco the only company that makes these kinds of systems.

And second, can you use one of these detectors to quantify an R vs an S enantiomer - even when they completely co-elute - thus making chiral separation unnecessary.

Much Thanks.

[Kostas Petritis]

When I was looking quite some time ago on these systems my understanding was that you can quantify these enantiomers but not with great sensitivity which might be a problem if you want to make sure that you have one enantiomer and not the other (i.e. for pharmaceutical applications).

Another issue is that you maybe want to upscale your chiral chromatography in order to purify your compound and use it for toxicological studies (which in this case again chiral detection won't do the job).

I wonder what is the legistation in these matters. Do they accept chiral detectors as a mean for reporting the absence of one enantiomer in the presence of the other?

[Wayne Way]

Astec/Supelco offer a chiral detector called the Chiralyser. It is based on optical rotation. Jasco offers two chiral detectors - a polarimeter and a circular dichroism (CD) detector. PDR-Chiral offers a polarimeter detector.

All have different advantages I am sure. The Chiralyser has high sensitivity and a stable, single wavelength lightsource for long life and high reproducibility.

[Bruce Hamilton]

There are other companies that make chiroptical HPLC detectors. eg
http://www.sthenocorp.com/products.htm

There have also been several reviews of chiroptical HPLC detectors, eg
Chiral liquid chromatography contribution to the determination of the absolute configuration of enantiomers.
J Chromatogr A. 2004 May 28;1037(1-2):311-28.
Roussel C, Del Rio A, Pierrot-Sanders J, Piras P, Vanthuyne N.

Generally, the detectors are expensive, usually have to be used with a conventional detector, and the enantiomers must be, at least, partially resolved. The chiroptical detectors based on vibrational circular dichroism seem to have attracted the most attention recently.

The general rule was ( may still be ) that if the injection volume ( uL ) x concentration ( % ) x specific rotation is greater than 100, then a chiroptical detector should be suitable.

A WWW search on chiroptical HPLC detectors should help.

Please keep having fun,

Bruce Hamilton