Unambiguous Characterization of a Single Test Sample by Fluorescence Spectroscopy and Solvent Extraction without Use of Standards

We show that a test sample containing several components can be analyzed unambiguously by a two-dimensional spectroscopic technique, such as fluorescence, if it can be split into two aliquots of unequal component concentrations. Standard spectra are not needed, nor is it necessary to make assumptions about regions without spectral overlap or about spectral shapes. The requirements are that the spectral response is linear and that the two-dimensional contribution from each component can be factorized into a product of its one-dimensional responses: I (λ 1,λ 2 ) = c i I i (λ 1 ) I i (λ 2 ). In fluorescence spectroscopy this is the normal situation for noninteracting species. The approach is illustrated on a test sample containing three components, which is split into aliquots by solvent extraction. Even though the components' spectral responses overlap extensively, all spectral features were correctly reproduced in the analysis.