The MCR analysis for each of the pairs of spectra (pure bulk spectrum, i.e., the dispersing medium spectrum and mixture spectrum, i.e., the NP-containing sample spectrum) was initiated by using a set of reasonable but arbitrarily chosen initial guesses for the mathematical concentrations of the two components in the samples. For the bulk component, the numbers used for that purpose, were 1 and 0.98 in the dispersing medium and the NP-containing samples, respectively. On the contrary, For the solute-correlated component, the respective numbers were 0 and 0.02. Broadly speaking, since prior knowledge about the system is not inherently required for MCR as a method to work, the initial guesses need not be very accurate; nevertheless, realistic initial guesses and constraints lead to results that better describes the reality. However, for only a pair of spectral data series, choice of the initial guesses is not at all critical, as long as (A) the orders of their magnitudes are not too distant and (B) the solutecorrelated component is defined by fixing its concentration value at zero for the sample made up purely of the bulk component.