inaccurate gradient baseline

[jiang295]

gradient is not accurate. I put 0.1% acetone in methanol as B solvent, pure methanol as A solvent and run from 0% B to 100% B. baseline should be straight if gradient is accurate. however, my baseline fluctuates a lot as showing below. anyone knows reason?
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[bisnettrj2]

Read through this article by John Dolan and Jonathan Gilroy from LCGC. It should help you figure out what's going on with your pump, outside the on-board diagnostics and tests you may have in your instrument software.

http://chromatographyonline.findanalyti ... rticle.pdf