Abstract Some basic troubleshooting. This chapter describes a number commonly occurring chromatograms where peaks show unexpected behaviour: compounds elute earlier, later, together, no peaks show up or other effects. The examples will help you to diagnose your chromatogram as well as to verify your hypotheses of the possible causes.
LevelBasic
Retention has decreased
List four (or five if you can) possible causes for this 
problem
How would you verify the suspected cause for this problem?
Retention has increased
List four (or five if you can) possible causes for this problem
How would you verify the suspected cause for this problem?
Short Retention times
List four (or five if you can) possible causes for this problem
How would you verify the suspected cause for this problem?
No separation takes place
List two possible causes for this problem.
Peaks are overlapping
List the possible causes for this problem
Rank in proper order which you would do first. Basic factors are :
- Ease of operation
- Probability that this is the problem
Peak is "tailing"
List four possible causes for this problem
each possible cause
Peak gets "shoulders" or is splitting
List possible causes for this problem
possible cause Peak is "fronting" 
List 2 possible causes for this problem
possible cause
No signal at all
List six possible causes for this problem
Describe how you would verify (in the lab) each possible cause
Unexpected peaks show up
List three possible causes for this problem
Describe how you would verify (in the lab) each possible cause.
Example 1: no sample
List possible causes for this problem above (example 1).
Example 2: very fast peaks
Possible cause?
