Concentration Of Surface-active Agent Research Articles

Mechanism of drug absorption from micellar solution. I. Absorption of solubilized vitamin A from the rat intestine.

Mechanism of drug absorption from micellar solution was studied through use of drugs which exist predominantly in micellar phase. Particular systems chosen were vitamin A acetate and vitamin A alcohol-Polysorbate-80. Contrary to the notion that the only form in which the drug penetrate the membrane is free drug, both vitamins, entrapped almost completely in micelles, were absorbed fairly well, but not as such, form the rat large intenstine. Disappearance of the vitamins from the perfusate proceeded by two phases, the rapid (initial 15 minutes perfusion period) and the slow phase (follwing 60 minutes period). In the former, extent of the absorption of the vitamins were dependent on the initial concentration of surface-active agent, whereas in the latter, no such tendency was observed. It was demonstrated that in the very early stage of absorption, vitamins solubilized in micelles are absorved onto the membrane, which being favored by the surface-active agent and in the slow phase, absorption now becomes rate-limited by the partition or release of the vitamins from adsorbed micelles to the mucosal layer of the membrane. Despite the large effective surface area, disappearance in the slow absorptive phase of the vitamins from the solution circulated through the small intestine was smaller compared with the large intestine.

INTERACTION BETWEEN DISPERSE DYE AND SURFACE ACTIVE AGENT

Interaction between disperse dye and surface active agent in water was investigated with the continuous variation method in optical density (Y function) and electro-conductivity. Samples used were 1, 4, 5, 8-tetra-aminoanthraquinone and two kinds of anionic surface active agent, sodium dodecyl sulfate (SDS) and sodium dodecylbenzene sulfonate (SDBS). In order to simplify the conditions the experiments were made throughout of the concentration of surface active agent below CMC. The experimental results suggested the formation of the compound DmSn and of the socalled “complex” DxSy (D: dye, S: surface active agent) as a result of interaction of the surface active agent used as dispersing agent with both the fine-crystalline dye and the molecularly dissolved dye in aqueous medium (in the case of SDS m:n=1:2, x:y=1:4 and 1:1, in the case of SDBS m:n=1:1, x:y=1:1). From these results it is deduced that in general in the bath of disperse dye an equilibrium like the following may be achieved.

Bacteriophages of L-Glutamic Acid-Producing Bacteria

The effect of the non-ionic surface-active agents (SAA) on the infection of phage P465 of Br. lactofermentum was examined by adsorption and one-step growth experiments as a part of the basic study on the prevention of phage-infection in the industrial fermentation. Among various SAA tested, polyoxyethylene stearyl ether (POE-SE), polyethylene glycol monooleate (PEG-MO) and polyoxyethylene sorbitan monostearate (Tween 60) had remark-ably demonstrated the selective inhibition of phage infection. The effect of the above three SAA was apparently restricted to the initial adsorption step of phage infection, for the phage already adsorbed would not be affected by exposure to SAA. However, the results of one-step growth experiment indicated that Tween 60 inhibited not only the phage-adsorption, but also the maturation of phage already adsorbed in the host cells. The rate of the inhibition was found to be directly related to the concentration of agent. And, the most effective adsorption-inhibition was exhibited at the critical micelle concentration of SAA. The concentration as used in our experiments did not affect the viability of either phages or the host cells. The results also indicated that the inhibition of phage-adsorption was due to the action of SAA on the surface of the bacterial cells rather than on the phage. This is supported by the observation that preincubation of phage with SAA did not affect either the sub-sequent adsorption rate or the plaque-forming ability of the phage. In contrast with above, a short-term exposure of bacterial cells to SAA caused an apparent change to the cell surface which was only partially restored by washing repeatedly. Moreover, the inhibitory effect of SAA on phage-adsorption appears quite specific in the phage-host system.

Dissolution kinetics of benzoic acid in high concentrations of surface-active agents

The dissolution kinetics of benzoic acid has been studied in the presence of certain surface-active agents. The addition of tyloxapol, polysorbate 80, sodium lauryl sulfate, and poloxakol to the dissolving fluid increased the apparent solubility of benzoic acid. In considering the experimentally determined dissolution rate as a function of solubility, it appears that the dissolution process in solutions of tyloxapol, polysorbate 80, and sodium lauryl sulfate concurs with the diffusion layer concept, while the dissolution process in the presence of poloxakol is best described by an interfacial barrier model.

Absorption and Excretion of Drugs. XXIX. Effect of Surface-active Agents on Rectal Absorption of Sulfisoxazole from Oily Base

Effect of various types of surface-active agents on the rectal absorption of sulfisoxazole from cocoa butter was investigated by the blood level determination with rabbits. Blood levels were in general increased with increase of surface-active agent, and decreased by addition of the large amount. Surface-active agent accelerated the release of the drug from the base to dissolution medium. On the other hand, surface-active agent reduced the absorption rate of the drug from aqueous solution. These results suggest that the increase of the drug absorption at the low concentrations of surface-active agents is due to release acceleration, but the reduction effect on drug absorption in their higher concentrations is due to predominance of absorption reduction over release acceleration. Cetyltrimethyl ammonium bromide especially stimulated the drug absorption in the very low concentrations.

The action of surface-active agents in aqueous milling processes, especially at low concentrations

It has been shown that the degree of dispersion achieved when 16.17-dimethoxyviolanthrone is milled in water is greater, the higher the concentration of surface-active agent, even in the range where there is more than sufficient to maintain a monolayer at adsorption equilibrium. This is interpreted in terms of the availability of agent molecules in the locality of fragmenting particles. At lower agent concentrations, phenomena of aggregation and coarsening on prolonged milling have been observed, and the progress of a milling of this type has been interpreted in the light of the measured adsorption behaviour of the surface-active agent in question on the solid. A study of the progress of a milling of copper phthalocyanine in a relatively dilute solution of a surface-active agent showed similar behaviour, an initial increase in surface area of the solid being followed by a marked decrease.

Ultrafiltration of solutions of nonionic surface active agents

From the results of ultrafiltration of nonionic surface active agents, we have obtained the conclusions as follows. 1: In aqueous solutions the micelle volume increases with increasing concentration of surface active agents, at least until a few percent. 2: In ethanol solutions, it seems that there are no micelles. 3: In aqueous ethanol solutions, the micelle volume becomes smaller with increasing amount of ethanol, but it is not yet clear the accurate concentration of ethanol, at which the micelle disappears.

Studies on Antistatic Property of Surface Active Agents

The behavior of antistatic agents applied to textile fibers was studied. Surface active agents (SAA) used in this work were purified highly. Surface electric resistivity of fibers treated with SAA solutions and specific conductivity of the solutions were measured. Besides, the effect of added electrolyte and the orientation of SAA to the fibers were also studied.Surface electric resistivity decreased as the concentration of SAA solutions increased and in the vicinity of the critical micelle concentration of SAA it once increased and again decreased in the higher concentration. It may be concluded that antistatic effect is greatly affected by the micelle state of used solutions.Inorganic salts added to SAA solutions did not afford electric conductivity to the fibers but contributed to the change of the micelle state of SAA solutions. The addition of NaCl to the solutions of cationic surfactants (CSA) resulted in an increase in the sorption of CSA by fibers and was effective in antistatic effect, but NaOH was not. It is suitable for antistatic treatment to use CSA together with electrolyte having the tendency to salt out CSA and to make micelle molecular weight larger. Antistatic effect of fibers treated in organic solvent was less than that treated in water, because of low micelle molecular weight.Piles of Nylon, Dacron, cotton and glass fiber treated with SAA were dispersed in benzol-water and the orientation to fibers of SAA was studied by observing in which of the two layers they dispersed. Following result was obtained; CSA in benzol, anionic surfactants in water. But piles treated with Na dioctyl phosphate which is the only antistatic agent of anionic surfactants dispersed in benzol or interface. It may be due to the orientation of SAA to fibers that CSA and Na dioctyl phosphate exhibit good antistatic properties.

THE HYDROLYSIS OF PROPYL BENZOATE IN AQUEOUS SOLUTIONS OF SURFACE-ACTIVE AGENTS.

Abstract The effect of cetrimide and sodium lauryl sulphate on the alkaline hydrolysis of emulsions and solutions of n-propyl benzoate has been investigated and compared with results obtained previously in cetomacrogol solutions. Evidence is presented to show that the rate of reaction depends on the degree of saturation of the dispersion expressed as a “Saturation Ratio”, which is the ratio of ester concentration to its solubility in a given concentration of surface-active agent. The hydrolysis rate of solubilised ester decreases with increase in surface-active agent concentration while the effect of such an increase in concentration on the hydrolysis rate of emulsified ester depends on the nature of the surface-active agent. The initial rate in sodium lauryl sulphate and cetomacrogol is independent of concentration, but in cetrimide the rate increases with cetrimide concentration until sufficient is present to solubilise the ester.

Separate determinations of the surface excesses of surface-active ions and of gegenions at the air-solution interface

The physical meaning of the slope of surface tension vs. the logarithm of the concentration under various conditions has been analyzed thermodynamically. The surface excesses (concentrations) of surface-active ions and of gegenions at the air-solution interface have been determined from the graphs of ( 1) the surface tension vs. the concentration of surface-active ions under the condition of a definite concentration of gegenions, and of ( 2) the surface tension vs. the concentration of the gegenions under the condition of a definite concentration of surface-active ions. The surface concentrations at the air-solution interface of aqueous solutions of perfluoro-octanoic acid, potassium perfluoro-octanoate, and barium perfluoro-octanoate were Γ C 7F 15COO- = 4.0, Γ H+ = 1.8; Γ C 7F 15COO- = 3.9, Γ K+ = 2.0; Γ C 7F 15COO- = 3.3-2.8, Γ Ba++ = 1.0-0.9. in 10 −10 mole/cm. 2 below, but near, the CMC. The surface excesses determined from the graphs of the ordinary surface tension vs. the concentration of surface-active agent were 5.8, 5.9, and 4.3-3.7 in 10 −10 mole/cm. 2. These values were of course equal to the respective summation of the surface excesses of surface-active ions and of gegenions within experimental error. The fact that the surface concentration of gegenions is about one half that of surface-active ions is noteworthy.

The oxidation of solubilised and emulsified oils. Part III. The oxidation of methyl linoleate in potassium laurate and cetomacrogol dispersions.

Abstract Oxidation rates of aqueous dispersions of methyl linoleate emulsified and solubilised by potassium laurate and cetomacrogol, have been measured manometrically at 40°. Emulsions of methyl linoleate oxidised at a greater rate than solutions. The relation between concentration of surface-active agent and oxidation rate of emulsions is complex, and appears to depend on the relative amounts of emulsified and solubilised oil present. Poor agreement was obtained between oxidation rates calculated from peroxide values, chemical and polarographic, and those calculated from oxygen uptake. The results are discussed. An increase in light absorption at 234 mμ in the early stages of oxidation was observed. An uptake of 2.5 mol. oxygen per mol. of methyl linoleate was estimated to occur during the primary oxidation reaction in the presence of cetomacrogol, and 1.5 mol. oxygen per mol. of methyl linoleate in potassium laurate dispersions. The possible mechanism of the reaction and the nature of the oxidation by-products are discussed.

Studies on the mechanism of coagulation

ζ-potential measurements have been carried out on positive silver iodide sols in the presence of anionic surface active agents at various concentrations. The conditions employed were the same as those used for the stability measurements described in Part I. The curves of ζ against log concentration of surface active agent were compared with those expected theoretically on the basis of a single adsorbed layer of surface active agent, and from the gradient of the curves at the point of zero ζ-potential the free energy of adsorption of the first adsorbed layer was calculated. It was found that to explain the form of the curves at higher surface active agent concentrations, i. e. negative ζ-potentials, postulation of a second adsorbed layer was required. The free energy of adsorption of the second layer was found to be lower than the first and to be consistent with the idea of adsorption occurring due to van der Waals attractions between the hydrocarbon chains. Combination of the potential data with the stability (W) data from Part I gave curves of log W against ζ which were compared with those expected theoretically.

The Effect of Various Ointment Bases on the Percutaneous Absorption of Salicylates II : Effect of Surface-Active Agents

The effect of the inclusion of several concentrations of surface-active agents in four different types of ointment bases on the percutaneous absorption of salicylic acid and sodium salicylate was determined. Hydrophilic ointment, petrolatum, hydrophilic petrolatum containing water, and polyethylene glycol ointment were modified either by varying the concentration of surface-active agent present in the U. S. P. XV formula, or by adding varying amounts of surface-active agents to those bases in which none was originally present. Sorbitan monostearate, polyoxyethylene 20 sorbitan monostearate, and polyoxyethylene 40 stearate were studied as representative of lipophilic and hydrophilic surface-active agents of the nonionic type. The results indicate a correlation between percutaneous absorption and the degree of interaction of the polyoxyethylene groups present in the hydrophilic surface-active agents with the salicylates.

Circulation in liquid drops

A number of aspects of the motion of drops through liquids are discussed with a view to clarifying the physical picture of the mechanism by which the liquid/liquid interface influences the transfer of momentum and mass across it. Internal motion and distortion are shown to affect drag characteristics at relatively high Reynolds numbers (100 to 1000). The Hadamard and Hill vortex models are compared. The internal velocity distribution in a spherical drop is shown to agree with both models but external motion in the Stokesian region is only predicted by the former. At higher Reynolds numbers where a potential flow regime prevails, the external motion is more closely described by Hill’s model. Vortices do not form in a drop until the Reynolds number reaches a critical value depending on the state of the interface and the viscosity of the drop liquid. Bond & Newton (1928) predicted that interfacial tension was the only variable affecting the transition but additional effects due to impurities and to the polarities of the component liquid molecules are also important, not only regarding the onset of vortex formation but also in relation to the extensiveness of circulation when under way. The presence of impurities such as very small concentrations of surface-active agents, although lowering the interfacial tension, greatly reduces the velocity of circulation in the vortex.

An electron microscope and X-ray examination of the influence of dodecylpyridinium iodide on the formation of silver iodide sols

Examination of the influence of dodecylpyridinium iodide on the formation of silver iodide sols (conc. 5 × 10−4 M), by turbidimetric measurements, revealed the presence of four coagulation regions with intermediate regions in which stable sols were formed. The form of the sol particles and the structure of the coagula, formed under these conditions, has been investigated in detail using the electron microscope. Selected area microelectron-diffraction and X-ray diffraction examination of the various regions showed that the silver iodide particles generally had a hexagonal structure but under some conditionsγ-cubic silver iodide was also present. It was found that at low concentrations of surface active agent (10−6M) the rate of sol particle growth was enhanced but at higher concentrations (10−3M) it was greatly retarded. The phenomena observed were interpreted on the basis of the strong adsorption of dodecylpyridinium ions onto the negatively charged silver iodide surface.

The Nature of the Particle Surface in Hevea Latex and Pastes of Rubber Hydrochloride and Polyvinyl Chloride

Abstract The colloid-chemical properties of natural rubber latex are influenced by many factors, such as the pH, the concentration of surface-active agents and the presence of ions of different kinds. Many of these factors have been studied intensively. However, it has usually been assumed that the surface of the rubber particles consists of plain hydrocarbon. Up to now it has been impossible to investigate the properties of the surface free from adsorbed soaps and proteins, for the removal of these surface-active agents results in coagulation of the latex. But the latex particles can be obtained in a hard and nontacky form by hydrochlorination and crystallization according to the methods of van Veersen and the author. The various surface-active agents can then be removed by filtering, washing, and extraction with organic solvents, without the loss of the surface by coagulation of the particles. The reactions of most organic chemical groups with hydrochloric acid are fairly well known and, though the original properties of the surface may be modified to some extent by the hydrochlorination, an investigation of the surface of rubber hydrochloride may give useful information regarding the properties of the original surface of the rubber particles. A suitable method for studying the nature of the surfaces of various rubber hydrochlorides would be to investigate the rheological properties of concentrated dispersions in organic media. Dispersions in plasticizers were selected, in the first place, because the experimental work is then not complicated by the volatility of the solvents, and secondly, because these dispersions in plasticizers are of some technical interest, since they can be used for the preparation of monofilaments from rubber hydrochloride.

INVESTIGATION UPON THE SPINNING OF VISCOSE

The adhesive force of viscose to the surface of nozzle in a coagulation liquid is generally considered to cause the clogging of nozzle hole. An apparatus to measure the adhesive force is showed in Fig.1, 2mg of viscose was put between the pieces and as soon as the pieces with viscose was soaked into coagulation liquid, one piece was pulled down to the tangential direction of it's surface, and the force to tear off the pieces was measured. The adhesive force can be exprsessed with the quotient of the force to tear off the pieces by the perimeter of piece surface.The results were as follows:1. With the increase of concentration, H2SO4 decreased the adhesive force and Na2SO4 and ZnSO4 incrased it.2. With the increase of concentration of surface active agent in viscose or coagulation liquid, the adhesive force decreased but some surface active agents had no influence in the adhesive force of viscose, though they could decrease the surface tension.3. The influence of surface active agents on the adhesive force can be affected by Na2S and Na2CS3. In one case the adhesive force decreased with the increase of their concentration and in another case the adhesive force increased. This shows that there might be a mutual reaction of these salts and the surface active agents, and it might also affect either the adhesion of viscose to the surface or coagulation and regeneration process of viscose.

The oxidation of solubilised and emulsified oils. I. Oxidation of benzaldehyde in potassium laurate and cetomacrogol dispersions.

Abstract The solubility of benzaldehyde in solutions of potassium laurate and cetomacrogol, has been measured at 20°. Oxidation rates of emulsified and solubilised benzaldehyde have been observed manometrically at 25°. The effect of concentration of surface-active agent on the oxidation rate of benzaldehyde has been studied. Emulsified benzaldehyde oxidised at a greater rate than solubilised benzaldehyde. Emulsified benzaldehyde was more susceptible to the action of copper catalysts than was solubilised benzaldehyde. Possible reaction mechanisms and loci of reaction are discussed.

La mesure automatique de la période de chute de l'électrode à gouttes de mercure, et ses applications analytiques

A description is given of an electronic chronometer, controlled by a photo-electric cell, which enables one to measure the drop rate of the dropping mercury electrode to an accuracy of within 0.1%. The relation between the drop rate and the concentration of surface-active agents is discussed and the analytical potentialities of the method are briefly examined.

The effect of a surface-active agent on mass transfer in falling drop extraction

The effect of small additions of sodium oleyl- p-anisidinesulphonate on the rate of extraction of iodine from aqueous solutions with 4·2 to 22·3 mm 3 falling droplets of carbon tetrachloride has been determined. The droplets were formed in a section of the column containing water and surface-active agent only, thus eliminating extraction during drop formation and securing a stationary adsorption state before the droplets entered the extraction column proper. A maximum reduction in the overall mass transfer coefficient of 67 to 68% was observed for all droplet-sizes, with an addition of about 6 × 10 −5 g surface-active agent per 100 ml aqueous solution, whereas much larger additions were practically without further effect. The results have been analysed in terms of an interfacial resistance coefficient R isec/cm, which was found to be independent of the droplet size, and to obey the equation C S = 5·4 × 10 −9 ▪ where C S is the aqueous concentration of surface-active agent in g/100 ml, and R i is calculated on a solvent basis. The equation is derived on the assumptions that the interfacial resistance is proportional to the interfacial concentration of surface-active agent, and that the adsorbed film is of the “vapour expanded” type. An adsorption isotherm for a “vapour expanded” film is given. It is concluded that the results cannot easily be explained in terms of interfacial turbulence or transfer of turbulence, but that there is some kind of interaction between the adsorbed film and the diffusing solute, as postulated by H utchinson [2] and G arner and H ale [3]. The rate of fall of the droplets was also found to decrease sharply on the addition of small amounts of surface-active agent, the reduction amounting to 7 to 10% for all droplet sizes at about 2 to 3 × 10 −5 g per 100 ml. Much larger additions resulted in a more gradual decrease.