By diana on Thursday, March 21, 2002 - 11:25 pm:
Hi, i am confronted with the following problem. i am utilizing a LcC/MS system (finnigan) and a "standalone" HPLC (Shimadzu). The colums i use are Luna C18 2x50 mm (LC/MS) and 4.6x50 mm (HPLC). the gradient is from 5-95% acetonitril in water with 0.05% TFA. Flow 0.5 ml/min and 1 ml/min.
A substances i want to analyse (or even a standard)elute on the LC/MS for instance with ~65% MeCN. The same substance elutes von the HPLC with ~30% MeCN. And its resproducible. I guess i check allready everything like: solvent bottle connetions, columns (i swaped them), charge of solvent etc.
I hope that someone has an idea what went wrong or what i did wrong.
Thanx for helping me!
By Anonymous on Saturday, March 23, 2002 - 06:40 am:
Good morning Diana,
Part of the reason is the flow rates, to have the same linear velocity in the 2mm column you need a 0.2mL/min flow. This accounts for some of the r.t. shift. The other big reason is probably due to a difference in the dwell volumes between the two LCs, this will elute compounds at different appearant %MeCN on the two instruments. Hope my little bit helps somewhat.
Rgeards,
Mark
By diana on Monday, March 25, 2002 - 03:42 am:
Hi Mark,
i really forget to include the dwell volume in my "method transfer". I will check this.
I already adjusted the flow. I scaled up from the 2mm colummn with 0.5ml to max. 2.5 ml with the 4.6mm column, and also in/decreased the time axis resepctively
Posting is currently disabled in this topic. Contact your discussion moderator for more information.