Window factor analysis of methylene blue in water

The aggregation of methylene blue (MB) in water was studied by factor analy sis (FA) of the visible spectra over a wide range of concentration from 1.0 00 x 10(-7) to 1.600 x 10(-2) M. Abstract factor analysis of data with mult iple sources of error (AFA-MSE) revealed three MB species. The concentratio n profiles and spectra of the species were extracted by window factor analy sis (WFA). The profiles were interpreted to be due to MB monomer, dimer and a trimer containing one chlorine atom. The dissociation constants of the d imer and trimer were determined to be 1.5 x 10(-4) M and 3.2 x 10(-11) M-3 respectively. Copyright (C) 1999 John Wiley & Sons, Ltd.