Chromatography Forum

Hey,
We have a HPLC method for primary and secondary amines using NITC as a derivatizing agent and UV detection which works fine. It does not derivatize tertairy amines so we are loking for something else that may work. We only have UV detectors for the HPLC no MS or ELSD, etc. We read a series of papers from one group that FMOC would work for trimethylamine but after trying it we are convinced the product they measured is a byproduct of the reaction or a product that several other tertiary and secondary amines form with FMOC.
We scanned the literature and can't find anything that seems to derivatize tertiary amines which I guess from their structure makes sense unless one one of the C-N bonds is broken?
Anyone here know of any HPLC-UV methods that work for tertairy amines especially trimethyl and triethy?
We are looking for reporting limits ~1 ug/mL or lower hopefully .1.
FYI we are also exploring gc-fid and are having some luck but don't have a good column to try and are having problems with DCM reacting with trimethlyamine. Someone else is in charge of this part of the project...
FYI we only have an isocratic IC and TMA coelutes with calcium and other amines. We dont have the newer gradient IC..
We are looking to develop and air method for tertairy amines sampling on acidic media and then desorbing in water and neutralizing and/or extracting into hexane/dcm etc...
One thought we had would be to react the amines with an UV absorbing aicd such as picric but then how to analyze? The salt/complex would disassocate unless the PH was lower than the PKa of picri acid which is less than 1 and we can't run that low pH on our HPLC or columns....
any thoughts wuld be appreciated!
EG

Hi There,
I have quantified TMA by GC but using NPD detector and i can get down to 0.001mgs....let me know if need help with it...
I wonder if you can help me, i am analysing residual DETA in a reaction mix and am trying to adapt osha 60 methodology which involves derivitsing with NICT...however i am using a c8 column and i dont really see the thiourea paek or at least i am unable to identify this peak...can you help, please.
thanks
Lubna

Lubna,
We use our own method but its similiar to the OSHA methods-On a C18 column the NITC peak elutes pretty late-26+ minutes on our conditions while DETA elutes at 12 minutes-280nm-try making a 5 and 50ppm standard and see if the peak goes up? There are several impurities/decomposition products of NITC that may interfere with DETA under your conditions so make sure to run a NITC blank first.C8 is less retentive than C18 so you may have coelution.
I can email you our workup if you'd like?
Let me know if you need anything else
Re TMA on NPD we had some luck with that but since our samples were acidic we had to neutralize them before analysis and had variable results..we havent worked on the method since then..I'd be interested to hear what type of samples you were running and sample prep methods? We could see ~1ug/mL maybe less.
Eric

I will post you the method tomorrow as I live in UK and I am at home presently.

The TMA is a byproduct produced during a manufacture of one of our products. We have used C tubes to trap the TMA and then desorbed with CS2. Standrds were prepared in CS2 and the response was linear. Very good reproduciblity and accuracy. We have also carried out a gas bomb anaysis and again level detected were low.

As for the DETA , this is used in a reaction and we want to ascertain that it has been used up during the reaction. I have used the OSHA 60 method but like I said used a C8 column but will try a C18 tomorrow or may even try a CN column.

It would be great if you could send me a summary of your work as that would be a great help.

I will send you a copy of the TMA chromatogram and the gc CONDITIONS. tomorrow.

ThankS fOR YOUR HELP

LUBNA

MY EMAIL ADDRESS IS

tshafiq@talk21.com

You can email me your address and i will send you my stuff.

Thanks

lubna

Hi ,
Did you mange to look at your method today?
I am on a c18 column right now with Acetonitrile /water mobile phase . Did you make up your standards in DMF as per OSHA METHOD?

Any help would be appreciated.

Can anybody send me the GC column condition for trimethylamine, Injector temp, carrier gas, I am unable to identify peak for trimethylamine.