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Posted: Thu Sep 10, 2009 5:11 am
by unmgvar
Mohan
have you tought of doing sample concentration using SPE?
Posted: Thu Sep 10, 2009 10:02 am
by Alex Buske
Hi Mohan,
If you can filter through 0,45µm then is is not highly viscous. I would avoid dilution with water, as sample solution stability can arise(dependeing on the polarity of the API).
Is the pressure rise permanent or just after injection? If it is permanent something migth deposit on the column. If it is temporarily, then try a Precolum with larger particles as "mixing and dilution Part".
Alex
Posted: Thu Sep 10, 2009 4:22 pm
by Uwe Neue
The point is that dilution with water may increase retention and thus enable a larger injection volume. Your customer may not have thought about this possibility.
Posted: Sun Sep 13, 2009 3:15 am
by mohan_2008
Thanks guys,
let me explain the situation correctly. Our low concentration suspension sample is 0.01mg/mL.
We get the samples "as is" from the client. And the main concern is -
Can we inject the sample suspension straight onto a column at this concentration. We are trying to improve the throughput and less analytical work, if we can succeed in injecting the suspension straight.
Yes, dilutions tend to make the injection easier. But, this is a situation wherein, I am not allowed to dilute the suspension to any ratio.
I am looking at the possibility of a column that is suitable for a straight suspension injection. High pore size is good, since even if the retention drops it is not a major factor, as long as the suspension can get flushed out the column with minimal rinse.