Chromatography Forum

Hi guys!

Such as subject. I must create a GC method to determinate the concentration of DMF as residual solvent in my drug. I use a GC with head space system and FID detector.

What is the best way that I must follow? I must use more Sample volume in head space vial, or minor volume? What is the partition coefficent (K) of DMF?

Thank you very much!

Your system must not have bare metal in the flow path or at least, it will be much more difficult to measure DMF.

It might be less difficult to do a dissolve and shoot method into your GC to measure DMF. But this will require at least daily maintenance of the injection port.

If it not possible to GIVE you a method for your drug as there are too many unknowns about the matrix to be helpful. It will be necessary to find a suitable solvent and one that will tolerate higher temperatures than are normally used in HS analysis. Any thick film methyl silicone should be adequate for the analysis. A shorter column would be better over a longer column.

Try a library or the Web to find specifics for your situation, but again they must be compatible with your unknown matrix.

best wishes,

Rod

Why my GC must not have metal bare? My Headspace (HS 40 by perkin elmer) use a metal needle to hole HS vial. In this needle pass carrier gas. It's a problem?

Such as solvent I use DMSO (190° bp). It's polar, than DMf is much soluble in it. But I work with 155°C of sample temperature. The column that I use is 30 m x 0.32 x 1.8 um It's a Zebron 624. I must use this because DMF isn't the only solvent that I must search in my powder drug.

I believe you can adjust the temperature for the needle in the PE.

DMSO will probably elute too closely to the DMF. Add some DMF to a vial and test for yourself.

You need to do some library work before you start, but of course, freebies here are so much easier.

DMF is not trivial but can be done. It is one analyte that for ME, works better as a dilute and shoot method residual solvent methodology.

good luck,

Rod