CAPILLARY ELECTROPHORESIS ANALYSIS OF POLYHEMATOPORPHYRIN, A PHOTOSENSITIZER USED IN PHOTODYNAMIC THERAPY

Free solution capillary electrophoresis and micellar electrokinetic capillary chromatography are used to separate components in polyhaematoporphyrin (PHP), a preparation similar to Photofrin which is used as a photosensitizing agent in photodynamic therapy. PHP is known to contain haematoporphyrin (HP), protoporphyrin (PP), hydroxyethylvinyldeuteroporphyrin (HVD) and a mixture of ester, ether and carbon-carbon linked oligomers. The use of reference samples of HP and PP, together with partially dehydrated HP, has allowed assignment of HP and HVD peaks in the electropherograms of PHP in 20 mM phosphate pH 6.9 and 20 mM disodium tetraborate pH 9.2 buffers using sodium dodecyl sulphate in the range 0-100 mM. Changes in the pattern and areas of monomer peaks and oligomer distribution following base hydrolysis (which cleaves ester linkages) and acid hydrolysis (which cleaves ester and ether linkages) yields information consistent with that from HPLC studies.