System Suitability - USP 621/CDER FDA - meaning and why would this be a useful to implement? Discussion 1- Peak Tailing one factor in System Suitability.
If I were a betting person - I think I would pick Peak A….however Peak B would probably cause me a bit of angst and Peak C- I would definitely be losing my edge as a chromatographer.
What is this parameter - Peak Tailing ….it can tell you a lot about HPLC method performance. What does it encroach on ? Peak Resolution which will be the next topic.
What is the cause of Peak tailing and non-asymmetrical peak shape?
A) hanging around way too long either in the mobile phase or the stationary phase
B) Column has over 15,000 injections, I think its time to throw it out
C) I think I overloaded the column - like a lot!
D) What was my pH again of my buffer?
E) How old is the guard column again - oh that’s on my maintenance log right?
F) may be my tubing is a big old - and valves a bit dirty - time to clean. Problem with Dead Volume?
A-F would all be the right answer. Column chemistry plays a big role in peak tailing and overall system maintenance, keeping a HPLC column log and activating “injector” number within software systems can help to monitor performance.
which peak here is the “bad actor” - although not super concerning- THCA definitely is “peak tail” vulnerable- why ?
The predicted pKa values are all around 2.9 which is approximately equal to the pH of the mobile phase (if 0.1% formic acid modified) so one might expect the acid groups to be about 50% ionized and more polar- although the high organic content of the mobile phase will tend to stabilize the neutral molecule over the ionized form and thus reduce the effective acidity (increase pKa). The observed elution suggests significant additional lipophilicity for the addition of a carboxylic acid group-where most molecules are neutral in this system.