Convenient Estimation for Counterion Dissociation of Cationic Micelles Using Chloride-Sensitive Fluorescence Probe

Abstract

The concentration dependent properties exhibit a break point due to the micellization.The CMC of surfactant is usually determined by plotting those properties as a function of concentration. The other important property of ionic surfactant solutions is the degree of micellar counterion dissociation, which has been used to be quantified by the two-site model (7,8). From this simple model one can calculate the α by using the concentrations of "free" ions in the aqueous bulk phase and "bound" ions in micellar phase. The model has successfully The MQAE probe was developed to study the transport of chloride ion in liposomes (11).The MQAE are highly polar and membrane impermeant, which has suitable physical properties for measurement of the concentration of free chloride ion. When the cationic MQAE is introduced to cationic surfactant solutions, the MQAE will tend to partition in aqueous bulk phase due to the low octanol-water partition coefficient in addition to the electrostatic effect.The fluorescence behavior of water-soluble MQAE can be expected to related to the chloride ion concentration in aqueous bulk phase. Fig. 2 shows the Stern-Volmer plots for quenching of MQAE fluorescence by various cationic surfactants. The fluorescence intensities of MQAE 5 were found to decrease in the presence of CTAC, TTAC, TDBAC and DAC. The observed quenching can be ascribed to the free chloride ion dissociated from the surfactant. All experimental data gave linear plots below their CMCs. The slopes of plots, K SV , below CMC are summarized in Table 1. The K SV for CTAC agreed very closely with that of NaCl. The K SV for surfactant monomer tend to decrease with decreasing length of the alkyl chain. The decrease in

Micellization behavior of mixtures of amphiphilic promazine hydrochloride and cationic aniline hydrochloride in aqueous and electrolyte solutions

“…Hence, degree of association (α =(1−g)) decreases. The degree of dissociation (g) decreases with increase in electrolyte concentration [39] and may decrease with micellar growth [40]. Also, with the increase…”

Quaternary ammonium compounds in soil: implications for antibiotic resistance development

“…From Table 1, it is clear that alkyltrimethylammonium compounds (ATMAC) and DADMACs, show correlations exist between increasing hydrophobicity and decreasing critical micelle concentration. Table 1 also illustrates that data on CMC are incomplete and incoherent between authors as experimental setups vary (Asakawa et al 2001;Lemić et al 2005;Marcotte et al 2005;Diress et al 2007;Cepeda et al 2013). Several studies have reported calculated values for the octanol-water partition coefficient for QAACs, although, these are not valid due to the surfactant nature of this compound class.…”

Electrochemical Behavior of Catecholamines and Related Compounds at In Situ Surfactant Modified Carbon Paste Electrodes

“…The anionic surface active agents: sodium dodecyl sulfate (Laurylsulfate, LS) (critical micellar concentration in water, cmc ¼ 7.4 mM [27]), sodium decylsulfate (DS) (cmc ¼ 33 mM [28]), with the same hydrophobic group but shorter aliphatic chain length, and sodium dodecylsulfonate (DD), with 12 carbon atoms in the hydrophobic chain but a different polar group, were obtained from Sigma (Spain). The cationic surfactants: N-cetyl-trimethyl ammonium chloride (CTAC) (cmc ¼ 1.31 mM [29]), N-decyl-trimethylammonium chloride (DTAC) (cmc ¼ 24.4 mM [29]) and dodecylpirydinium chloride (DP) (cmc ¼ 16.8 mM [30]) were purchased from Merck (Spain). These compounds were used for the study of the electrochemistry of acidic catecholamine metabolites.…”