To address this problem, we report on a new analysis protocol to quantitate a model multi-functionalized AuNP system that would allow us to accurately calculate the concentration of different molecules attached to the surface of AuNPs. Initially, AuNPs were synthesized and functionalized with Zn Porph and Cyt C. The concentration of the molecules conjugated to AuNPs could not be accurately determined due to overlapping absorption spectra. A method was then devised to deconvolute the merged absorption spectra of the two types of conjugated molecules using CASA-XPS. This enabled accurate identification of the peak heights of each type of conjugated molecule so the concentrations could be calculated for each type of molecule. This method can be used as a guide by the researchers to tailor binding parameters for obtaining multifunctionalized AuNPs for the desired application.