Absorption and Fluorescence Properties of Chlorophyll a and b and Pheophytin a and b in Aqueous Solutions of Nonionic Surfactants

Abstract

Absorption and fluorescence properties of chlorophyll a and b and pheophytin a and b in aqueous solutions of six species of nonionic surfactant were examined, respectively. The interaction between chlorophyll and surfactant was considered using two parameters; molecular refraction and inorganicity/organicity ratio. Chlorophyll was most soluble in Triton X-100 [average addition molar number of ethylene oxide (EO) group: n =9.5] solution or polyoxyethylene mono-p-octylphenylether [n = 10] (POOPE-10) solution. Chlorophyll a and b had larger solubilities in the surfactant solutions than did pheophytin a and b. However, the molar extinction coefficients and fluorescence quantum yields of the chlorophylls in the surfactant solutions were smaller than those in organic solvents, such as acetone. Consequently, the interaction between the magnesium of chlorophyll and the oxygen atom on the EO chain and labilization of the excited states of chlorophyll by water molecules became apparent. © 1994, The Japan Society for Analytical Chemistry. All rights reserved.