Troubleshooting Peak Problems

Nexera Virtual Advisor

Symptom	Cause	Solution
Retention time fluctuation	Varying mobile phase composition	Use a fresh mobile phase preparation and check the composition of the new mobile phase.
Retention time fluctuation	Unstable flow rate	Examine the pump function and take corrective action as necessary.
Retention time fluctuation	Fluctuating ambient temperature	Relocate the instrument or protect the current location from excessive environmental effects. Use a column oven.
Retention time fluctuation	Column performance has deteriorated	Examine the column oven function and take corrective action as necessary. Replace the column.
Retention time fluctuation	Check valve is not working properly	Clean the check valve in an ultrasonic bath or replace as necessary. Pump 2-propanol through the check valve to clean it.
Retention time fluctuation	Blockage present in the needle or plumbing	Clean the high-pressure valve with reverse cleaning of the flow lines. Remove the blockage with reverse cleaning of the flow lines.
No peaks/very small peaks	No plate in the specified rack position	Insert a plate with samples in the specified rack position.
No peaks/very small peaks	Needle contacts the bottom of the plate or misses the target	Determine the stack application (microtiter plate or deep-well microfilter plate) and set the needle stroke accordingly. Perform rack teaching for the SIL-20A/20AC, if applicable.
No peaks/very small peaks	Flow line blocked with plate material particles	Remove the blockage with reverse cleaning of the flow lines.
No peaks	No mobile phase flow	Examine the pump function and take corrective action as necessary.
No peaks	Insufficient sample in vials	Add more sample to the vials.
No peaks	Detector is not connected or is faulty	Examine the detector connections and take corrective action as necessary.
No peaks	Column performance has deteriorated	Replace the column.
No peaks	Blockage in the injection flow lines	Check and correct the content of the user-written program. Clear or replace any blocked plumbing.
OVER is displayed	Leak - flow lines	Find and repair the leak.
OVER is displayed	Dead volume between the flow line connections	Examine flow line connections. Reconfigure the connections to eliminate any dead volume.
OVER is displayed	Connections between the pump and column are reversed	Reconfigure the plumbing connections.
OVER is displayed	Column performance has deteriorated	Replace the column.
OVER is displayed	Recorder pen is below the baseline	Press [Zero] to return the pen to the the baseline. Remove the blockage with reverse cleaning of the flow lines. Replace the needle or the plumbing.
Poor reproducibility	Varying mobile phase composition	Examine the pump functionality and take corrective action as necessary. Use a fresh mobile phase preparation and check the composition of the new mobile phase.
Poor reproducibility	Needle seal has deteriorated	Replace the needle seal.
Poor reproducibility	Leak - flow lines	Find and repair the leak.
Poor reproducibility	Insufficient flow line rinse or no rinse solution	Increase the RINSE VOL settings or replenish the rinse solution. Perform the PUMP HEAD FLUSH operation. PURGE or RINSE the flow lines.
Poor reproducibility	Fluctuating ambient temperature	Install unit in a room with minimal temperature variation.
Poor reproducibility	Column performance has deteriorated	Replace column.