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- Posts: 4
- Joined: Tue May 23, 2017 7:21 am
I have a question about baseline drift.
We have a method for determining protein concentration, and we use Waters H-Class system and Poros A20 column 2.1 x 30 mm for this method.
This method has a very dramatic Mobile phase gradient as below:
0.00 to 5.00 min: 100% Mobile phase A
5.00 to 5.01 min: 100% Mobile phase A to 100% Mobile phase B
5.01 to 10.00 min: 100% Mobile phase B
10.00 to 10.01 min: 100% Mobile phase B to 100% Mobile phase A
10.01 to 15.00 min: 100% Mobile phase A
Where,
Mobile phase A: PBS solution with pH 7.3
Mobile phase B: PBS solution with pH 2.5 (pH is adjusted with 85% phosphoric acid)
The baseline has a shape of hat with wide flat brim because of the dramatically changing gradient (like this, _Π_; I'm sorry for my poor explanation..). Fortunately, the drift (crown of the hat) is usually very small so that it does not affect on data processing and test result.
However, sometimes, the drift (crown of the hat) was increased more than about 10 times of usual baseline (like a toy soldier's hat, I'm sorry for my poor explanation again..), and we couldn’t find the root cause of this problem.
What could cause this huge drift?
The source for preparation of MP A and B is same, and we tried replacing mobile phase/column and washing the system to solve this problem, but it was useless.
Any suggestion will be greatly appreciated.
Thank you very much for reading my question!!