M Ringuet | PubMed Health

PubMed1995

Separation of overlapping spectra from evolving systems using factor analysis. 3. Fluorescence spectra of hematoporphyrin IX di-n-propylether diethanolamide.

Fluorescence spectroscopy of hematoporphyrin IX di-n-propylether diethanolamide (HPPEEA) in aqueous solutions, with and without SDS, was obtained in the pH range from 0.1 to 13. At pH greater than 3, HPPEEA in water solutions gives spectra complicated by aggregation whereas in aqueous SDS solutions, the aggregation is greatly reduced. Factor analysis is used to separate the spectra of the individual species from the experimental spectra. Five and four species are identified in pure water and in aqueous SDS solutions, respectively. The predominant species are: two free bases at pH higher than 6; one monocation at pH near 4; and two or one dications at pH lower than 2.5. The intensity signatures are related to the ionic distribution and to the aggregation situation of HPPEEA at different pH.

Amphotericin B↗

PubMed1995

Separation of overlapping spectra from evolving systems using factor analysis. 4. Fluorescence spectra of hematoporphyrin IX.

Fluorescence spectra of hematoporphyrin IX (Hp) in water and in aqueous SDS solutions are obtained in the pH range 0.1 to 13 to determine the ionisation state of the molecule as a function of pH. In water, the spectra are complicated by aggregation which is quite severe near pH 4. In aqueous SDS, the aggregation is much less violent. Factor analysis (FA) is used to identify five species in the fluorescence spectra in each series of solutions. The distribution curve of these species as a function of pH is also obtained. By comparing the spectra and the distribution curve of Hp with those of HPPEEA, an ethanolamide derivative of Hp that does not contain the carboxylic groups (Part 3), the species are identified. For Hp in water we have obtained the following species: the dication in two allotropic forms in the pH range 0 to 5; the monocation (with the charge on an imino nitrogen) in the pH range 2 to 7; and the free base in the pH range 3.5 to 13. The monocation observed by the second derivative technique revealed three subspecies. For Hp in aqueous SDS we have obtained the following species; one dication in the pH range 0 to near 4; one monocation (with the charge on an imino nitrogen) in the pH range 0.5 to 9; three free bases (with no charge on the imino nitrogen) in the pH range 4 to 13. Of the latter, one species is the neutral molecule, another is a dianion (with the charges on the carboxylic side chains), and the third one appearing at pH higher than 10 is an allotropic form of the dianion.

Factor Analysis, Statistical↗