Chromatographic TroubleshootingBaseline symptoms203C It can also result from valve operations: If valves are beingswitched during a run, examine the valve time program to see ifthe change coincides with a valve operation.C This symptom also can occur if the septum suddenly begins toleak; Avoid the problem by changing septa regularly.C Offset•see troubleshooting procedure for the particular detectorin use.Wander and driftBaseline wander or drift may occur when a flow or temperature setting ischanged. If the system is not stabilized at the new conditions beforestarting a run, some baseline changes are to be expected. Cases followingassume that sufficient stabilization time has elapsed since the lastchange in operating conditions.Wander and drift are often accompanied by noise, discussed below.1. Baseline moves steadily upscale or downscale (drift) during the run:C This is most frequently seen during temperature programming:Operation with a single column (no column compensation) atmoderate to low attenuation causes this. If dual columns are used,check that the signal mode is correct for column compensation.C It is also possible the compensation is insufficient (upscalemovement) or too great (downscale movement).This cause of drift is minimized by thorough column conditioning.Operating at lower oven temperature also helps but prolongs theanalysis. Use of a chromatographically equivalent column withhigher temperature limit is also possible.
