DETERMINATION OF PHOTODESTRUCTION QUANTUM YIELDS USING CAPILLARY ELECTROPHORESIS - APPLICATION TO O-PHTHALALDEHYDE-LABELED BETA-MERCAPTOETHANOL-LABELED AMINO-ACIDS

Photodestruction quantum yields, Phi(D), were determined for o-phthala ldehyde/beta- mercaptoethanol-labeled protein amino acids in aqueous a lkaline solution using trans-azobenzene actinometry. The Phi(D) values ranged from 0.020 to 0.062; the highest were obtained for amide-conta ining amino acid derivatives (Gin and Asn; Phi(D) = 0.062 and 0.054, r espectively). The average maximal number of fluorescent photons obtain ed from the chromophores ranged from 6.4 to 19.0 per molecule. We show that Phi(D) values can be determined with the help of an internal sta ndard using capillary electrophoresis with laser-induced fluorescence detection. Generally, good agreement between the Phi(D) values obtaine d in this way and Phi(D) values obtained using trans-azobenzene actino metry was found. Furthermore, we show that knowledge of the analyte's photochemical properties assists identification of components separate d by capillary electrophoresis.