anything can decreae the retention time?

[slimshady]

I found my retention time decrease as the number of injections increase.

It is not becuz of the flow rate. I use a TTBB which does not absorb on column to confirm it.

Is the water in the solvent can decrease the retention time>?
i am using a dancial chiralpak AD-H column

If there is the sth bulit on the column, the retention would not change too much between two continous injections. But in my case even between two injections ( the duration time is 15min) the retention time changed a lot.


Anyone has any suggestion for that??
i am getting crazy about it...

P.S i have flushed the column this afternoon. But it is of no use....

[DR]

Add details (gradient profile, mobile phase composition, flow rate...).

[tom jupille]

If you want to check out possible causes, look in the LC Troubleshooting Wizard at http://www.lcresources.com/resources/TSWiz/hs30.htm but, as DR suggested, there is not much advice that we can give without more details about your separation.

[ntruong]

Hi Slimshady,
Is your retention time shifted inward or outward? You may have to allow more equilibration time before the injections are made. How about pre-condition your chiral column with mobile phase overnight and try it out? Do you sonicate the mobile phase and turn on in-line degasser?