Study of local anaesthetics. part 203*. micellization of heptacainium chloride studied by spectral methods in aqueous solution

Abstract

The formation of micelles of the local anaesthetic heptacainium chloride (substance, XIX) in aqueous solution was investigated by the pyrene absorption and the pyrene I1/I3 ratio methods, respectively by optical density (OD) method for surface curvature measurement. First, the absorption spectroscopy in UV/VIS region was based on studying changes in characteristic absorption spectrum of pyrene in presence of surfactant. The resultant plot of the sum of absorbances for the entire key pyrene maximum as a function of the total surfactant concentration showed, in the region of the critical micellar concentration, a usual sigmoidal increase. The fluorescence emission spectroscopy in UV/VIS region of spectrum by the probe pyrene, second procedure, was applied for determination of the cmc from the detections of the pyrene I1/I3 ratio as a function of the surfactant concentration. The pyrene ratio data were fitted by the Boltzmann-type sigmoid of declining progress. The third (OD) method used required microliters of surfactant solutions and standard microplate absorbance measurements. © 2013 Galis̀inová J, et al.