By Anonymous on Thursday, April 1, 2004 - 11:36 pm:
Can anyone assist us with an explanation for ghost peaks in the following situation:
A reverse phase analysis at 210nm using mobile phase of 0.1% TFA, 0.5% MeOH, 0.8% THF and 98.6% Water.
We observe both positive and negative peaks which do not appear related to the solvent front or the sample. Samples are made up in mobile phase.
If we inject a sample of just mobile phase into our mobile phase the peaks still appear.
As we inject more samples the size of the positive ghost peak increases.
We are using a new Shimadzu HPLC system.
Are the ghost peaks caused by TFA and if so why would we still see them when we inject mobile phase as our sample ?.
Any advice would be welcomed.
Julex
By Uwe Neue on Friday, April 2, 2004 - 03:52 pm:
At 210 nm, you are likely to see all the components of your mobile phase (except for water). Inject the components on their own, and see if the retention time of the peaks correlates with them.
The mobile phase components all contribute to the background. If there is a slight difference in the composition between you sample and the mobile phase, you will see peaks, positive or negative.