I was wondering if anyone could give me advice on what hardware might be the most sensitive for amino acid detection. We have used reverse phase LC in the past but someone might have a better newer method. Thanks Al

If you focus on sensitivity one option could be an "old principle" using pre-column dansylchloride derivatisation and fluorescence or even more sensitive peroxyoxalate chemiluminescence detection.

If you use HILIC-mode separation of amino acids the mobile phase is suitable for MS-detection.

you could also try the reverse phase-electrochem approach. OPA-thiol precolumn derivitization. This one is also flourescent.
-how small of a sample volume are you talking?

Allan;

Long ago Dr Gerkhe developed procedures to form TMS derivatives of amino acids containing trifluoromethyl groups. These gave the derivatives good volatility and excellent response in ECD. I remember that the method was somewhat difficult to apply to all the amino acids, but the detection limits were in the range you want to obtain.

It would help you to ask Pierce or Regis for information about these old techniques.

Good Luck;

Benjamin

This is Al! Thanks all for your advice on low level AA detection the volume we are shooting at is 20ul. We have accomplished this in the past with a Beckman Gold system but it's been years. What about a LC-GC system from Waters. do you think this is more sensitive detection. Thanks Al

Nowadays, you can further decrease the injection volume by using lower ID columns and still have fmol sensitivity.

I think that actually the most sensitive one should be after derivatization to obtain high fluoresent derivatives and use lazer induced fluorescence detectors.

I know about the PicoTag approach of Waters for amino acid analysis but have never heard of an LC-GC method (at least from Waters). Maybe Uwe could answer this.

There are also several LC methods lately which deals with direct (underivatized) amino acid analysis and detection with mass spectrometry, amperometric detector or chemiluminescence nitrogen detector.

Kostas

There is a newer and very rapid method available. Look under AccQ Tag at the Waters webside. The derivatization is very fast, seconds, and the tag is fluorescent. The combination of both gives you high sensitivity and an simple method.

In our analysis of a synthetic amino acid (baclofen) we quickly rejected the dansyl chloride and the OPA method (I think you have to be a wizzard to use these successfully) and had reasonable results with FMOC (also most sensitive with fluorescence detection). One can commercially obtain a lot of FMOC-amino acid derivatives which is invaluable in developing the method. This availability also shows that the derivatives are more stable than practically all competitors.
I checked Waters´ site, but did not find any comparisons of AccQ Tag and the FMOC method, anybody?

I was wondering if anyone could give me advice on:
Can I use AccQ method to determine primary and secondary amines? If the answer is yes, Could you please give me some references?
Thank you very much
ovallesd@ula.ve

There are examples on the Waters webside, showing proline, for example. Check at waters.com!