Chromatography Forum

In the analysis of Related Substances we have found the diluent peak at RT of impurity some time it comes very close to the Impurity peak some time seperated from impurity. We have check this is not the carryover peak ( by long run, by Change the new column also ). But its area is 0.05% of the main analyte peak. My only worry is that if this peak merges with impurity, it will give the wrong results in the stability . One thing we observed that this peak does not appear in the fresh mobile phase but after 3 hours is peak appear in the diluent this we come to know when we injected five replicate s of the diluent then it comes consistently. What i have to do?

Mobile phase KH2PO4 buffer: ACN
30 70

Column Zorbex Cyno 25x4.6

Wavelength 227nm

Diluent Mobile phase

Aruna

Something is wrong here. If your diluent is, in fact, your mobile phase, then you should not see any peaks when you inject the diluent only (other than the usual t0 noise caused by the injection process itself).

So, first question: what is the k' for the impurity peak?