Chromatography Forum

A HPLC analysis for Impurities using polymeric reversed phase column was conducted. The diluent (i.e. Blank) contains phosphate buffer in methanol.
In the chromatogram for the Blank, 2 peaks were observed in the first few minutes. In the sample chromatogram, the peak areas for these two peaks were much larger. For quantitation of impurities, are these 2 peaks considered to be due to sample interaction with the diluent and ignored?

I don't think there is an applicable answer here, before you've investigated the matter more experimentally and found out what is the nature of these peaks.
F. x. inject several blanks in a row and see whether the peaks diminish or just “stay” the same. Also do the same with the sample. And finally inject one sample followed by one blank, then 2 samples followed by a blank. See if there is a difference between these two blanks.

Best Regards

I agree with Denko.Inject 6 blanks and see whether the peaks appear everytime.Inject high concentration of sample and then blank to find carry over.