Peak Shape Issues

Question

(perbiously) 
 (now)

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.

Dr. Know · Accepted Answer

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

First do your system suitability test with your system of proof the valve is fine 
 Change the guard column 
 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) 
 Regards, 
 Norbert

Peak Shape Issues

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