We all know it and we all hate it: the dreaded “ghost peak” in reduced CE-SDS (see below). He is a devious one that appears randomly and disappears before you can understand the root cause. Let’s put this peak to sleep! Here is what we know about him:
- He appears between the two non-reducible species peaks (~24 minute retention time with the 20 cm meter separation)
- Sample buffers with pHs ranging from 6.5 to 9.0 produce this peak
- His magnitude can vary: 0.2% up to 2.0% time correct area
- Re-injection from the same vial will replicate this peak (i.e. it does not go away with time)
- Only re-prepping the sample will make it disappear
- Heat sources and vials have been the targets of investigations in the past
- These are contributing factors, but not the prime cause
- Some molecules produce this peak easier than others
- Changes in reducing agent concentration can mitigate the peak
We would like to see if there is a molecule characteristic, which when combined with the faulty heat sources/vials could manifest in the ghost peak. Please leave your comments through the contact form as to how you and your company have mitigated this peak and/or if you have discovered any possible links between structure function characteristics and the manifestation of this peak.
More information on the CEPharm CE-SDS Troubleshooting Parties and data collection.
We organize these troubleshooting working parties specifically and purposefully as CASSS, which is a not-for-profit organization.