PDA baseline noise (Guided Troubleshooting) - WKB206744

SYMPTOMS

• Baseline noise in PDA chromatogram
• SQT test failure for noise specification
• Issues with quantification at lower levels

ENVIRONMENT

• ACQUITY UPLC PDA Detector
• ACQUITY UPLC PDA eλ Detector
• 2998 Photodiode Array Detector
• ACQUITY Arc 2998

STRATEGY

1. For ACQUITY PDA, check the 250-psi back pressure regulator (WKB10081).
2. Ensure that the lab temperature is fluctuating within a normal range.
   1. Shield the detector as a workaround (WKB63875).
   2. Relocate the instrument if possible (WKB85306).
3. On ACQUITY PDA, m​​​​inimize refractive index effects if running at low UV wavelengths (less than 205 nm).
   1. Sonicate mobile phases (WKB1529).
   2. For QSM, place all lines in a single mobile phase bottle (WKB95837).
   3. If using a 30-cm column heater, insulate the column outlet lines (WKB1035).
   4. Confirm that the tubing from the Column Manager is routed correctly to the PDA and does not make contact with the lamp cable.
   5. If possible, turn on Median Baseline Filter (MBF) (WKB95839).
4. Check the fittings around the detector (WKB9652).
5. Inspect the flow cell.
   1. Clean the flow cell (WKB9482).
   2. For 2998, rebuild the flow cell (WKB13746).
   3. If necessary, replace the flow cell (WKB23351).
6. Replace the lamp (WKB20304).
7. Inspect the solvent manager for pressure fluctuations.
   1. If necessary, replace the check valve (WKB73348).
   2. If necessary, rebuild the pump (WKB74137).

ADDITIONAL INFORMATION