Chromatography Forum

Hi

can anyone reccommend an appropriate solvent to use whilst trying to seperate Methanol, ethanol, methylene chloride, Toluene and DMSO out of an API using a Headspace GC method. i have had troubles using DMF and am looking for the best alternative.

Thanks

Have you tried water? There is also DMI, but the last time I checked it was REALLY expensive (and toxic)

Thanks i might give that a go.

How about DMA as an alternative? any idea as to wether that would be appropriate?

What levels of DMSO are you looking for, along with those other analytes? I've never had much luck getting DMSO to partition at low levels, and it's going to be even harder in a high-boiling matrix like DMI, DMF or DMA.

As long as your analytical column separates DMSO and DMAc and its impurities (MMAc is one, DMF is another) I would try DMAc.

With DMAc it might be easier and more accurate to do a traditional dilute and shoot method but that would require a new method, validation, etc. and is not the answer to the question you posed.

By all means try the DMAc.

best wishes,

Rod

I am looking for DMSO at only 1000ppm, along with Methanol at 1000 ppm, ethanol at 1000ppm, methylene chloride at 500 ppm and toluene at 800 ppm.

Currently this is all development work and so the fact that validation would be required is expected. i am just trying to minimise the validation that would be required by resolving all the solvents in the one method, currently i have a method that is suitable for analysis of one supplier, which resolves the ethanol and methylene chloirde but due to my problems with the DMSO don't have a method for the seccond supplier which contains the Methanol, toluene and DMSO, i am waiting on a column to test out a method which uses Methylene chloride as the diluent, but like i said i would prefer to be able to seperate all the solvents in the one method to save time during validation.

thanks for all the help