- Peak fronting and peak distortion (see figure below)
- ACQUITY UPLC SM
- ACQUITY UPLC I-Class
- ACQUITY UPLC H-Class
- ACQUITY UPLC
- The sample diluent is too strong (stronger than gradient beginning) and Full Loop injection mode is applied.
- The weak wash solvent is too strong.
Weak wash issues are seen in Partial Loop (Pressure Assist) mode.
FIX or WORKAROUND
- Reduce the percentage of organic solvent in the sample diluent (sample diluent should be weaker or equal to gradient beginning).
- Reduce injection volume (dilute sample with weak wash solvent during injection).
- Change Injection mode to PLUNO (Partial Loop with Needle Overfill).