Troubleshooting Baseline Problems

Nexera Virtual Advisor

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Symptom Cause Solution
Drift Dirty cell lenses Dismantle the flow cell and clean or replace the lenses as necessary.
Drift Dirty flow lines Thoroughly clean flow lines.
Drift Faulty detector Check the detector function and take any necessary corrective action.
Drift Fluctuating ambient temperature Install the unit in a room with minimal temperature variation.
Drift Fluctuating flow rate Check the pump function and take any necessary corrective action.
Drift Impurities in the mobile phase - drift stops when the pump is off or an air cell is used Inspect the mobile phase and clean the flow lines.
Drift Lamp intensity has deteriorated - noise continues when an air cell is used Replace the lamp.
Drift Lamp not stabilized Start measurement 1 to 1.5 hours after the lamp was turned on.
Drift Lamp or flow cell is improperly installed Reinstall the lamp or flow cell.
Drift Leak - detector Examine the cell tubing and cell window for leaks. Clean and repair the leak.
Drift Mobile phase contains impurities or the column has not equilibrated Examine or prepare fresh mobile phase. Allow more time for column equilibration.
Drift Strong air current or large ambient temperature changes Relocate the instrument, or protect the current location from excessive environmental effects.
Drift and Noise Bubbles in flow cell Perform the bubble removal procedure.
Fluctuation Strong air current or large ambient temperature changes. Relocate the instrument, or protect the current location from excessive environmental effects.
No Change Faulty circuits Replace any faulty parts.
No Change Lamp is off Set the LAMP parameter to 1 or 2 to turn ON lamp power.
No Change RANGE set to 0 Enter an appropriate RANGE value.
Noise Cell lenses are dirty Dismantle the flow cell and clean or replace the lenses as necessary.
Noise External vibrations Reduce the external vibrations. Use a sturdy counter as a support.
Noise Impurities in the mobile phase - drift stops when the pump is off or an air cell is used Inspect the mobile phase and clean the flow lines.
Noise Lamp intensity has deteriorated - noise continues when an air cell is used Replace the lamp.
Noise Low lamp energy Replace the lamp.
Noise Strong air current or large ambient temperature changes Relocate the instrument, or protect the current location from excessive environmental effects.
Noise - two-wavelength mode Absorbances of mobile phase and sample solvent are different Select a wavelength with less absorbance or select solvents with closer absorbances.
Noise - two-wavelength mode Response value is too low Set the response to a higher value.
Noise - with pump stroke Pump pulsation Install a pump pulsation damper.
OVER is displayed Recorder pen is below baseline Press [Zero] to return the pen to the baseline.
Sawtooth Bubbles in flow cell Apply back pressure to cell outlet with a backpressure device or 0.3 mm I.D. x2 m tubing. Degas the mobile phase. Perform bubble removal procedure.
Spikes - continuous  Bubbles in flow cell Apply back pressure to cell outlet with a backpressure device or 0.3 mm I.D. x 2 m tubing. De-gas the mobile phase.
Spikes - random Bubbles in the flow cell Apply back pressure to cell outlet with a backpressure device or 0.3 mm I.D. x 2 m tubing. De-gas the mobile phase. Perform bubble removal procedure.
Spikes - regular Bubbles in flow cell Apply back pressure to cell outlet with a backpressure device or 0.3 mm I.D. x 2 m tubing. Perform the bubble removal procedure. Rinse the flow cell with 2-propanol. Use the supplied syringe.
Spikes - regular Pump pulsation Examine the pump function and take corrective action as necessary. Install a pump pulsation damper. Perform the bubble removal procedure.
Spikes - with pump stroke Bubbles in the flow cell Apply back pressure to cell outlet with a backpressure device or 0.3 mm I.D. x 2 m tubing. Rinse the flow cell with 2-propanol. Use the supplied syringe.
Swell Dirty cell lenses Dismantle the flow cell and clean or replace the lenses as necessary.
Swell Impurities in the mobile phase - drift stops when pump is off or the air cell is used Inspect the mobile phase and clean the flow lines.
Swell Lamp intensity has deteriorated - noise continues when air cell is used Replace the lamp.
Unstable Bubbles in the flow cell Apply back pressure to cell outlet with a backpressure device or 0.3 mm I.D. x 2 m tubing. Rinse the flow cell with 2-propanol. Use the supplied syringe.