HPLC Retention time shifting
Posted: Mon Aug 06, 2018 6:30 pm
We have two brand new Waters e2695 HPLCs, they run with the same gradient, solvents, columns, guard columns, etc. One instrument is running fine with no retention time shifts, the other is all over the place.....
Parameters:
-Gradient runs using HPLC grade Water, Acetonitrile and MeOH.
-use a Zorbax C18 column and guard column.
- runs are 40 minutes long
-detector is fixed at 360 nm
The instrument ran for 3 months with no problems. Currently, our retention times have shifted. The beginning compounds shift to the left and the remaining 2/3's of the compounds shift to the left and then to the right. Some have shifted by as much as a minute.
Pressure and delta are normal.
We have changed:
guard column and guard column assembly
check valves - done by waters technician
seal pack - done by waters technician
analytical column
sinker frits for all solvents
in line filter
Any ideas or suggestions are welcome!!!
Parameters:
-Gradient runs using HPLC grade Water, Acetonitrile and MeOH.
-use a Zorbax C18 column and guard column.
- runs are 40 minutes long
-detector is fixed at 360 nm
The instrument ran for 3 months with no problems. Currently, our retention times have shifted. The beginning compounds shift to the left and the remaining 2/3's of the compounds shift to the left and then to the right. Some have shifted by as much as a minute.
Pressure and delta are normal.
We have changed:
guard column and guard column assembly
check valves - done by waters technician
seal pack - done by waters technician
analytical column
sinker frits for all solvents
in line filter
Any ideas or suggestions are welcome!!!