2 Replies Latest reply on Dec 19, 2018 8:02 AM by howwhite

    1260 SEC baseline drift


      We have been seeing baseline drift in our SEC testing ever since we have had our new 1260 systems in use starting Jan 2018. I have run lamp diagnostic testing and everything has passed. We have seen different variations of this drift on all three of our HPLCs located in two different labs. The temperature in our labs have been pretty consistent as well. The drift slopes downward (see below). Our mobile phases are filtered using sterile nylon filters and the salts they contain are fresh HPLC grade. I have also performed a cell test to assess the flow cell as that testing passed with no issues.


      1260 Infinity DAD module G7115A and column compartment G7116A


      Example drift:



      Any feedback would be greatly appreciated.

        • Re: 1260 SEC baseline drift

          Just ran another SEC assay and here are the mobile phase injections with drift. As you can see the drift gets worse. Three injections Red is the first, then Blue and then green.


            • Re: 1260 SEC baseline drift

              Hello mmajkut,


                   I presume this is an isocratic method, but in case there is a proportioning valve in the flow path, such as with a Quaternary pump, bypass the gradient valve, or try premixing the solvents instead, or clean or replace the valve. Since this drifting is common to three LC systems it seems the cause is unlikely to be a hardware failure.  Column bleeding can be the cause. If you think this is possible flush the column with strong solvent; also improve the sample clean-up and use a guard column. You might need to replace the guard and or analytical column.


              Hope this helps !


              Howard White