By Anonymous on Thursday, May 13, 2004 - 03:13 pm:
Is DMSO a bad solvent to dissolve a sample in and inject onto a C18 column? I have heard that it is not good for a column to expose it to DMSO. Why (or why not)? Aside from the fact that it will absorb UV light and give a peak, I can't think of any good reason.
Thanks
By Uwe Neue on Thursday, May 13, 2004 - 04:32 pm:
DMSO is a strong solvent in RPLC, and it has a high viscosity. These two features can lead to peak distortion or even breakthrough of some of your compounds as unretained peaks with excess DMSO. On the other hand, it is a popular universl solvent. If you have a choice, I do not recommend to use it. If you do not have a choice, think about some dilution with mobile phase prior to injection.
By Anonymous on Tuesday, May 18, 2004 - 04:15 am:
We tend to have drugs which are dissolved in DMSO (insoluble in saline etc) , and we tend to set a limit of 1% DMSO in the final injection mixture. This has worked fine for us
By Anonymous on Tuesday, May 18, 2004 - 06:06 am:
Also there was an article published by Waters about high strength organic injection techniques. If I remember right, the injector is placed in the line from the pump with the organic and then the gradient was started after the injection. This presumes a gradient method, I doubt it would work for isocartic. You might drop your local Waters rep a note about this or it might be on their web site.
Regards,
Mark
By Uwe Neue on Tuesday, May 18, 2004 - 03:10 pm:
The at-column dilution method was developed for prep applications, where the volume of DMSO is large. It works both in gradient and in isocratic applications. It is commonly not needed for analytical separations.