Poor reproducibility for negative transitions with Xevo TQ-S - WKB73040

SYMPTOMS

• Poor reproducibility for negative transitions
• Positive transitions all acceptable

ENVIRONMENT

• Xevo TQ-S
• Quattro Premier XE

CAUSE

Large number of MRMs set up in positive and negative modes in the same time span of MS method

FIX or WORKAROUND

1. Separate MRM groups to minimize MRMs overlapping with negative retention time window.
2. Validate new MS method to ensure that positive and negative data are reproducible and acceptable.

ADDITIONAL INFORMATION