Low sensitivity with PDA - WKB197082

SYMPTOMS

• Poor sensitivity
• Noisy baseline
• Low disk space

ENVIRONMENT

• ACQUITY Arc
• Alliance HPLC System

CAUSE

Many customers use default PDA instrument method settings (10 points/sec sampling rate and normal filter time constant) during routine HPLC analyses. Those default values are suitable for UHPLC or even UPLC instrument methods when peak width is about 2-5 s. In the case of HPLC methods, default values lead to oversampling (increased noise, erratic peak shape, worsened performance in trace analyses).

FIX or WORKAROUND

1. Use detector settings suitable for the application. Take into account the relationship between sampling rate and peak width. For HPLC it is typically 1 or 2 points/sec.
2. Try different settings for the filter time constant.
3. For 2D data, try higher resolution values (4.8 nm or more). 

ADDITIONAL INFORMATION