when I use C18 Reverse phase column , TFA and acetonitrile as mobile phase , gradient elution at a flow rate of 0.5 ml/min , the retention time is around 3.58 mins and I am not sure about the peaks that are eluted , when i compare it with the whey I get the same pattern of peaks but at aroun 5.45 mins. Can someone help me how to analyse with the same. Thank you