Ensure column has been fully equilibrated if changing mobile phase; run 10-20 column volumes of new mobile phase before analysis.
Small changes in temperature can cause cyclic baseline rise and fall. This is more common with RI and conductivity detectors. Use a heat exchange pre-column to control temperature.
Nonhomogenous mobile phase typically cause upward baseline drift. Mobile phase may be contaminated, deteriorated, or prepared from low quality materials.
Contaminants in detector cell may cause drift; clean with strong solvent or passivate.
If strongly retained compounds are eluting, this can appear as broad peaks in subsequent injections which appear to be rising baseline.
Ensure the line after detector is not plugged, as high pressure cracks in flow cell window may produce noisy baseline.
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