Trouble with DMF by HSGC

[Charles A. Burger]

I have a method to run that is supposed to elute 4 compounds, MeOH, Acetone, n- butanol and DMF. I was able to check on the partition coefficients of the first 3 but DMF has eluded me. I feel that it would be much larger than the rest of my solvents by experience.

My problem is that the response of DMF is terrible and not very reproducible. I even added 1 gram of sodium sulfate in order to drive out the solvents better but it only helped the first 3. I'm quickly realizing that this method I've inherited may not be suitable. Here are some questions;

1) What will a longer pressurization time of the vial do to it's reproducibility?

2) Can someone point me in the direction of a good source of partition coefficients of common solvents use in the processing of pharmaceuticals?

3) Are the 3 other solvents effecting the DMF in a negetive way?

Thanks

Chuck

[chromatographer1]

Oh, how I miss St. Louis !

DMF by headspace will require you to have very deactivated transfer lines and the proper septum on your vials.

It will improve if you do a total evaporative or almost-total evaporative HS analysis with your sample.

Feel free to call or email me for additional concerns which would be too lengthy to type here.

best wishes,

Rodney George
Senior Research and Development Scientist
Gas Separations Research
Supelco
595 North Harrison Road
Bellefonte, PA 16823

814-359-5737 voice
814-359-5459 fax
rgeorge@sial.com

[Russ]

Here's a St. Louis flashback for you:

Where'd you go to high school? Anywhere close to highway "farty"?

[chromatographer1]

Hi

I went to HS in Pleasant Hill Mo and to the UM KC on the other side of the state.

But I spent 14 years living in St. Louis back in the 80s and 90s.

I still miss the frozen yogurt in the St. Louis Hills area.

And the Arch which I watched every day from my window at work and the barges going up and down the mighty Mississippi.

best wishes,

Rod

[Russ]

For the majority who have never been in St. Louis, "Where'd you go to high school?" is supposedly a common question here that is very rarely asked anywhere else. And "farty" is an approximation of how some say forty. There is also a "farty-far" that goes through the city.

[chromatographer1]

Russ,

You did not mention Ted Drews !

best wishes,

Rod