Chromatography Forum

Hello,

I am a student in a co-op work term trying to figure out how to properly analyze the above on GC. MDEA and it’s degradation products seem to work well on a DB Wax column but the water content is likely producing backflash and henceforth carryover. DEA has a poor response factor and THEED (one of the degradation components) doesn’t seem to show up (plus I don’t know where can one purchase THEED? Our one old old vial is almost empty). I’ve read about derivatization but we are trying to optimize a method for a high volume of samples and a low turnaround time. Any suggestions?

Well, Parker123, as a student first focus on your communications skills. For example, let me assume that DEA to you is diethanolamine and not diethylamine, and certainly not the drug enforcement administration.

We assayed diethanolamine and related materials in aqueous samples after dissolving in pyridine and derivatizing with BSTFA [N,O-Bis(trimethylsilyl)trifluoroacetamide, there's an abbreviation that's not ambiguous] on nonpolar capillary columns.

If you mean diethylamine: never mind.


I rarely injected aqueous solutions directly into the GC unless I was assaying hand sanitizers for ethanol content; but with aqueous injections one must keep the injection volume quite small as water expands a ton (scientific term) in the inlet. We would inject 0.5 microliters.

Hi Parrker123,

If DEA = diethanolamine, then THEED could be the compound with CAS number 140-07-8, otherwise known as ethylenediamine, a known degradation product of DEA. I think Millipore Sigma has this substance in technical grade (you may not want this), and TCI America has it as well. THEED is inexpensive.

BSTFA is an easy derivatization agent to work with, I concur with Consumer Products Guy on all points.

Best Wishes!

Sorry for the confusion. I am analyzing N-methyldiethanolamine and Diethanolamine. THEED is N,N,N-Tris(hydroxyethyl)ethylenediamine. THEED I can’t seem to find on sigma or Fischerscientific.

Thankyou for the derivatization information. We are trying to find an alternative method, as the only analyte of interest that doesn’t show up on GC is THEED.

Hello again,

Well, I'm less clear now on the use of BSTFA for these analytes. That said, if THEED = CAS number 150-39-0, then also the compound is called N-(2-Hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid.

One good site for buying info is Chemspider, another is ChemicalBook. Anyhow, MilliporeSigma sells this, and it is cheap:

https://www.sigmaaldrich.com/catalog/pr ... &region=US

TCI also sells this, and you should be able to get it via Fisher. CAS numbers are useful for searching sometimes.

Great!