Chromatography Forum

Hello all

I've been trying to estimate dimethylformamide (about 15% w/v) in an aqueous sample matrix, under the following conditions:

Column: DB-624 30 m
Carrier gas: N2 at 40 ml/min
Injector temperature: 200 deg C
Injector split ratio: 50:1
Injection volume 1 ul.
Detector: FID at 260 deg C.
Column oven temperature program: Initial 70 deg C, final temp at 225 deg C, @ 25 deg per minute.
Sample: DMF (about 15% w/v) in water or MeOH.

DMF elutes at about 7 mins.

Problem is, the peak tails badly, and I'm not getting reproducible peak heights.

Help!!

Use a Chromosorb 103 packed column, 2 meter fused silica lined 1/8" OD SS column, inject on column

Alternately, same tube but packed with 10% Apiezon L with 2% KOH on Supelcoport

A base deactivated Capillary Supelcowax 10 is a third choice.

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
rodney.george@sial.com

Thanks for the prompt reply, Rodney. I'll get in touch with the local Supelco dealer today.