For the detection of multiple oligopeptides, we have assumed the presence of DPP (derivative of IPP) with IPP immobilized over the same oxide surface. We have varied the percentage of DPP while keeping the NS constant. Even with a slight increase in DPP, the surface potential starts exhibiting the pHpzc due to the carboxylic sidechain of D [Fig. is joined with tripeptides by the carboxylic to form tetrapeptides. R is joined with dipeptides (-PP & -KP) by the carboxylic to form tripeptides. If the position of D is 2 nd /3 rd in the sequence of tri/tetrapeptide, it is joined by both carboxylic and amine groups amplitude, inflection points and pHpzc shift for higher DPP population constitutes the unique fingerprints for detection.