Chromatography Forum

Hello everyone!

I'm doing some R&D to find a suitable method to separate Triethylamine from Heptane in DMSO. Im using a ZB-624 60 meters, 320 µm x 1.8µm. If i inject Triethylamine alone we are having acceptable peak shape considering its an amine at the concentration of 500ppm. On the other hand Heptane is at 5000 ppm and is a very high and large peak eluting near TEA. In fact TEA is co-eluting and gives only a resolution around 1-1.3 (TEA is eluting before Heptane and tails up to the end of Heptane peak). Ive been trying split injection with flow from 1 to 5 mL/min and isothermal temperature from 30 degrees to 120 (mix of flow-temp). Bases deactivated liner was also use. HS parameters: Oven set at 100 degrees needle to 120 degrees and transfer line to 150 degrees. Ive also try ZB-5 as other column type and that give the same results. Is there anything you can suggest or if i use inapropriate conditions can you tell me what you would do to try to separate them?

Thank you in advance

Willy the GC

last year I did a R&D in Triethylamine and Trimethylamine in fish product.
I used SPME / GCMS technique and Supelco PTA-5 amine column. This column is specially designed for amine analysis that gives better peak shape.

In your method, did you try to use PTV injector? I think you can cooled the injector with liquid CO2 and trap the triethylamine. Remove the heptane by purging and increase in injector temperature. Further increase the injector temperature to inject the triethylamine into the column (system) for analysis

Thanks for responding Tolo,

Bad thing we dont have GC-MS where i work and unfortunately we are not using the cooling system that can work on GC. That would have probably work on GC-MS.....We are limited to GC split/splitless injector type with helium as carrier gas coupled to a Headspace sampler.

See ya later and thanks again!

Willy the GC