Peak Shape Issues



About a month ago, the peaks of my sample generally looked good. But this week, the same type of samples, resulted in a broad and tailed peak. All the conditions are the same. Is it because of loss of efficiency of the column?

It is a C18 Agilent column which was bought in Sep. this year, but we used it to run almost 40 samples a day, and the mobile phase is 10mM KH₂PO₄, 0.45mL/min.


  • Hi tsekayan,

    if you look at the last big peaks, you'll see that the tops look like two peaks close to each other elute. There are several possible causes for this:

    • Double injection because the rotor of the injection valve is damaged
    • Channeling in the guard column
    • Channeling/Broken packing bed of the column
    1. First do your system suitability test with your system of proof the valve is fine
    2. Change the guard column
    3. Clean the column according to the procedure in the user manual

    If the issue still persists the column is dead (and 2000-3000 injections is great, depending on the circumstances)



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