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
Any feedback would be greatly appreciated.