strange baseline jump

[afischer]

Hi All,

While running a 1ul solvent (hexane) blank on a HP5890 series II I get strange jump in the baseline at about 4.5 minutes. The baseline jumps from 5pa to about 9pa and remians at 9pa throughout the duration of the run. Troubleshooting has pointed toward the injection technique, but this trouble started after running several samples using a consistent injection techniques and getting no strange jump. Anyone know what might be going on here or how to fix it? Thanks

[upamaniah]

increase the split flow, minimise the column temp, change the glass wool, place right liner

vijay
india

[carrolr]

Data system : event (such as set baseline) ?
Gas flow change at time (4.5 min): split flow or carrier saver changes?
Is vent flow high enough (greater than 25 or 50 ml )?

Sufficient contamination in injector may cause background jump if flows to / from injector changes during run.