Chromatography Forum

Hi,

I would like to use Ehrlish Reagent (p-Dimethylaminobenzaldehyde) for
derivatization of some compounds, followed by RP HPLC. I have no experience of this derivatising agent and would like to have some litr ref
describing its use, limitations, reactivity, compatibility with organics etc.
A limitation is that Ehrlish Reagent is used in a high concentration (2 M) of HCl, but maybe this can be neutralized before injection on the column...

I am grateful for suggestions and references.

Regards,

Goran Karlsson
Octapharma AB
Stockholm

Erlich's reagent is used in the investigation of porphyrin's. Mixed in alkali with aminolevulinic acid (ALA) you get a reddish colour. Mixed with porphobilinogen (PBG) in acid you get a magenta colour. I think the bonding chemistry will be similar.

You should be able to get a UV-VIS detection method. If you are having difficulties, try complexing your Erlich's with your compound and do a scanning spectograph to ID the peaks.

As for refs, try searching for porphyrin methods or the Watson-Schwartz method, which is the porphyrin method. Clinical Chemistry or The Annals of Clinical Biochemistry may help.

It rather depends on what the compounds you have in mind to derivatize. Activated benzaldehyde reagents (Ehrlich's, p-anisaldehyde, vanillin) react with a variety of substances. You can also substitute sulfuric acid.