The Determination of Critical Concentrations for the Formation of Soap Micelles by the Spectral Behavior of Pinacyanol Chloride

Abstract

The absorption spectrum of pinacyanol chloride in aqueous solutions of anionic soaps changes sharply to that characteristic of its solutions in organic solvents over a short range of soap concentration. This effect is attributed to the formation of micelles, in whose hydrocarbon-like layers or cores the dye is solubilized. The concentration of soap at which this spectral change occurs is taken as "the critical concentration for the formation of micelles." In water the dye exhibits an absorption band at 5500A which disappears rapidly as the concentration of molecular soap increases. Thus, even 0.00006 molar potassium laurate gives a large effect. At about 0.0126 },If the 'i-band at about 4800A reaches a high intensity, which falls, with further increase of concentration, very rapidly close to the critical concentration. At 2.3 to 2.4 X lO--2 for potassium laurate and 6X lO-3 for the myristate the a-band (ca. 6150A) and the i3-band (ca. 5700A) begin to increase rapidly in intensity and these are considered as the critical concentrations, since these are the prominent bands in the solution of the

A Critical Assessment of Micellization of Sodium Dodecyl Benzene Sulfonate (SDBS) and Its Interaction with Poly(vinyl pyrrolidone) and Hydrophobically Modified Polymers, JR 400 and LM 200

“…This cationic dye undergoes a spectral transition (pink to blue) in anionic micellar solution. 28 The spectra are illustrated in Table 1. The results of the microcalorimetric runs are documented in Figure 5.…”

Uptake of fatty acids by jejunal mucosal cells is mediated by a fatty acid binding membrane protein.

“…For each oleate-albumin complex it was shown that over the initial 30-s incubation period uptake was maximal and linear, whereas it gradually decreased thereafter as a result of beginning cellular efflux ( Fig. 1; illustrated well below the critical concentration for the formation of micelles (24,25), it is evident that the apparent saturation kinetics were real and did not reflect substrate depletion. Uptake was also not limited by the oleate-albumin dissociation rates, since the maximal uptake velocity was at least 100-fold slower than the rate of spontaneous dissociation of all oleate-albumin complexes incubated (26 (4).…”

Anionic Gemini Surfactants: A Distinct Class of Surfactants

“…This method is not useful unless it gives a broad range of concentration values as cmc. It is applicable to anionic surfactants as they form charge transfer complex with the dye rather than cationic surfactants (15). Surface tension is probably most common method of determining the cmc.…”