Chromatography Forum

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....

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

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.

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?