How to Flush an HPLC Flow Cell to Troubleshoot Baseline Noise

This Information Applies To: Agilent UV LC detectors: Diode Array Detectors (DAD), Multiple Wavelength Detectors (MWD), Variable Wavelength Detectors (VWD)

Issue

The following procedure is recommended to flush a dirty flow cell and remove baseline noise.

Requirements

• Reverse the cell flow path by swapping the inlet and outlet lines. 
• If you suspect a clog or a partial obstruction of the cell, normally associated to an increase in pressure, follow the procedure described at this link first.

Steps to follow

Reversed phase applications

1. Open the Purge Valve of your pump. Set a flow of 5 ml/min and purge each channel for 5 min with HPLC-quality Water. During step 1, check that the solvent moves into the solvent line correctly and it goes out the Purge Valve. If it does not, check the state of the Solvent Filters and replace them.
2. Close the Purge Valve and flush the system. Set the flow rate at 1 ml/min. Let it run for 1 hour, with HPLC-quality Water. Make sure that the pressure does not exceed 60 bars during this step.
3. Flush the system with 100% Isopropanol (IPA) 1 ml/min, for at least 1 hour. Make sure that the pressure does not exceed 60 bars during this step.
4. Repeat step 2 then continue with step 5.
5. Swap the inlet and outlet lines of the cell flow and equilibrate the system with your solvents.
6. Check if the baseline issue observed initially disappeared. If so, reconnect the column and proceed in using the system. If the issue persists, please contact Agilent Technical Support.

Normal phase applications

1. Open the Purge Valve of your pump and purge each solvent line, one by one, with HPLC-quality Isopropanol (IPA). Set a flow of 5 mL/min and purge for 5 min. During step 1, check that the solvent moves into the solvent line correctly and it goes out the Purge Valve. If it does not, check the state of the Solvent Filters and replace them if needed.
2. Close the Purge Valve and flush the system with IPA and a flow rate of 1 ml/min. Let it run for at least 2 hours, with HPLC-quality IPA. Make sure that the pressure does not exceed 60 bars during this step.
3. Swap the inlet and outlet lines of the flow cell. 
4. Equilibrate the system with your solvents. 
5. Check if the baseline issue observed initially disappeared. If so, reconnect the column and proceed in using the system. If the issue persists, please contact Agilent Technical Support.

Learn how to effectively troubleshoot your Agilent UV Detector: HPLC-0GEN-2201e - Chromatographic Troubleshooting for HPLC e-learning course available from Agilent education