Spectral analysis of the aggregates of Stains-all in the presence of non-ionic surfactant Triton X-100 by principal component analysis method

Principal Component Analysis (PCA) method has been applied to determine the compositions of concentration induced metachromatic species of the cyanine dye Stains-all (Stal) in aqueous triton X-100 micellar medium. In different environments Stal shows a number of blue shifted peaks such as at 575, 535, 510, 470 nm etc. Among them we have been able to identify without any ambiguity the peaks at 575, 535 and 510 nm that have been assigned to the monomer, dimer and trimer of the dye. The molar absorption coefficient spectra of the individual species have also been determined. The equilibrium constant between monomer, dimer and trimer has also been calculated and found to be 7.17. (C) 1999 Elsevier Science B.V. All rights reserved.