Chromatography Forum

Hi
I want to make assay analyses to the memantine hcl tablets.But memantine hcl doesn't have UV abs. and I don't have MS.
What can you suggest ....
Sincerely..

210 nm, acetonitrile / 10 to 20 mM phosphoric acid, Atlantis T3 column

Hello xozkn,
Is this the first compound without a chromaphore to be tested in your laboratory? A quick online search indicates memantine has been analysed by in its native form by MS or by derivitisation. It's possible to form amide or sulfonamide species for detection by fluorescence or UV-Vis.

Alternatively, one would suspect memantine could be run underivitised or, for example, as trimethylsilyl or trifluoroacetyl derivitives by GC-FID.

edit: my colleagues would LOVE to try Uwe's suggestion, though

This compound has no UV activity and Atlantis T3 is not going to add any UV activity to the compound. So in this case Atlantis is good as any other RP column in your possession.
You can use ELSD with TFA in the mobile phase and any reverse phase column with low silanol activity. You can derivatize your compound with any common derivatizing agents (nitrobenzoyl chloride or any other UV active benzoyl chlorides, UV active isocyanates, arylsulphonyl chlorides, etc.). Make sure that your reaction is quantitative and fast. Check if are not making your molecule too hydrophobic, you can use either C8 or C18 column. If you use derivatizing agent you shouldn't be worrying about silanols as you will be converting amine to something else. Check "Handbook of Derivatives for Chromatography" by Karl Blau and John Halker to learn more.

I've found it hard to search out some UV spectral data for amines, however one web link seems to indicate primary amines display an absorption maximum (or maxima, if your resolution is great enough) somewhere around 210-220 nm while a tertiary amine is lower and close to 200 nm. I seem to remember being hampered by the use of triethylamine in one application at low wavelength due to very high background absorption; I don't know if this is a property of TEA or a result of degradation.

Wow....

Guys, the compound is a primary amine. You can see it at 210 nm, in the same way as one can see alcohols or sugars at this wavelength, provided you have a clean mobile phase background. This means that you need to use acetonitrile as the organic modifier, and a phosphate buffer or phosphoric acid. Phosphoric acid is simpler. In addition, this is for an assay in a tablet, which does not require supersensitivity.

One should not use methanol, since at this wavelength you will see the OH. Buffers based on organic acids absorb too much, and the detector goes blind. The reason for suggesting the T3 packing is that it is very stable at this pH, and at even lower pH values, contrary to MOST other C18s in the world. One also should not use packings with amide functions or carboxylic acid groups at this wavelength, since one will see the bleed from such packings.

OK, now you got the complete explanation for the original recommendation, which was:

210 nm, acetonitrile / 10 to 20 mM phosphoric acid, Atlantis T3 column

Didn´t I just ask this? Here it is again, Sealc_Tech: Do you have any spectra of amines?
I think some confusion arises because of misunderstanding of the "cut-off": It is the wavelength at which the absorbance approaches 1 (usually 10mm path).