Mitsuo Muramatsu

A radiotracer study on slow hydrolysis of sodium dodecylsulfate in aqueous solution

Abstract The rate of hydrolysis of sodium dodecylsulfate (SDS) in aqueous solution has been determined by measuring the radioactivity of 35 SO 4 2− formed in the solution of SD[ 35 S]S throughout the range of pH 1–4 and concentration of (1–4) × 10 −3 mole/l. The reaction was found to be so slow as to give 10 1–2 years, depending on the pH and concentration, for the half-life based on the second-order reaction scheme. The rate-determining step should be interpreted by neither self-radiolytic, nor photolytic, nor surface-induced, but by purely bimolecular processes due to the collision of a dodecylsulfate ion and a dodecylsulfuric acid molecule. A pretty good agreement is obtained between the experimental and theoretical values of the reaction rate as a function of pH and SDS concentration when pK of dodecylsulfuric acid is assumed to be 0.76.

Complex formation between N-dodecyl-β-alanine and sodium alkylsulfate as reflected in coadsorption from mixed solution

Abstract The surface excesses of N -[ 3 H]dodecyl-β-alanine (DBA) and an alkylsulfate (SAS) such as sodium decyl-, dodecyl-, or tetradecyl[ 35 S]sulfate have been determined at the surface of their equimolar solution by means of the sheet scintillation technique. The results are interpreted in terms of the concentration dependence of surface tension of the mixed solution by the use of the Gibbs adsorption isotherm under the assumption of a DBA/SAS equimolar complex in the solution interior and in the adsorbed phase. This seems to be adequate, as appearing in the tracer electrophoresis of a DBA/SAS mixed solution, as well as in the elemental analysis and IR spectrum of the precipitate formed at a high concentration.

Adsorption of tritiated surfactants at nitrogen/solution interfaces as determined by sheet scintillation counting☆

Abstract By the use of a counting device designed for determining the surface radioactivity of a solution of a tritiated compound, the adsorbed amounts (Γ) were determined for the solutions of (a) sodium dodecyl-2, 3- 3 H-sulfate (TSDS) in the absence of strong electrolyte, (b) TSDS in the presence of an excessive amount of NaCl, and (c) hexaethyleneglycol monododecyl-2, 3- 3 H ether. The Γ values thus obtained were in fairly good agreement with those calculated by the Gibbs adsorption isotherm for expressing the equilibrium surface tension (γ ∞ ) as a function of the surfactant concentration ( C ). Roughly, n in the conventional equation, Γ = − (1/ n R T ) × [ d γ/ d (ln C )], has been found to be 2 for the case (a) and 1 for the cases (b) and (c), as was predicted by many investigators. Discussions have been made to correlate precisely the surface tension data with the radiotracer results which provide direct information about the adsorption at the gas/solution interfaces.

Solid-Counting of Octadecane-1-H3.

A solid sample of octadecane-1-H3 was found to show a fairly good proportionality of the counting rate to the amount of the sample. Taking account of the synthetic process, nonvolatility, and spreadability of octadecane, this compound offers a possibility of being used as a standard sample for counting the radioactivity of tritium.

A radiotracer study on hydrolysis of methyl-14c palmitate in insoluble monolayers

Abstract Surface pressure and radioactivity ( R ) of insoluble monolayers of methyl- 14 C palmitate have been determined simultaneously as functions of time after spreading and of apparent molecular area ( A ) of the ester which was contained originally in the spreading solution. A large rate of decrease in A is accounted for by the processes involving evaporation of the ester and its hydrolysis, to which a small rate of decrease in R is due.

Radiotracer study on oxidation of oleic acid monolayer on aqueous permanganate solution

Abstract Studies have been made of the mechanisms of the oxidative processes of [ 14 C]oleic acid in its insoluble monolayer spread on aqueous permanganate solution by measuring simultaneously the time ( t ) dependences of surface radioactivity ( R ), apparent molecular area ( A ), and surface pressure (π). Infrared spectroscopic examination of the film material obtained by skimming the monolayer on permanganate solution indicates that the rate-determining intermediate involved in the interfacial processes is predominantly cis-epoxyoctadecanoic ( cis -epoxy) acid and none of the other oxyacids such as dihydroxy (diol), ketohydroxy (ketol), and diketo acids, those having been assumed as intermediate compounds by other investigators. A kinetic analysis of the A - R - π - t relationships leads to the conclusion that the major processes involve (a) relatively quick formation of the cis -epoxy acid in the monolayer and (b) the rate-determining desorption of the cis -epoxy acid into the underlying subphase. In parallel with (b), there is an interfacial reaction through which the cis -epoxy acid is fissured to form azelaic and nonanoic acids to be dissolved instantaneously into the subphase. An increase in π causes a retardation of process (a), an enhancement of process (b), and an enhancement of process (c) in the region of π ≦ ca. 15 dyn/cm beyond which it is retarded markedly. When the monolayer is spread on subphase without permanganate ion, an increase in π causes an enhancement of the desorption of oleic acid (much slower than that of the cis -epoxy acid), while the rate of the autoxidation is not affected by the molecular conformation at the air/water interface.

Insoluble monolayer of [14C] chloramphenicol palmitate at the air-water interface

Abstract The nature of the insoluble monolayer of chloramphenicol palmitate (CPP) at the air-water interface has been studied by simultaneous measurements of surface pressure, π, potential, ΔV, and radioactivity, R, of 14C-labeled CPP as functions of apparent molecular area, A, and time, t, elapsed from the delivery of CPP solution at the interface. The observed time dependences of π, ΔV, and R in relation to A have been accounted for only by reorientation of CPP molecules in the monolayer, with elimination of the possibilities of their evaporation, dissolution, and hydrolysis. The reorientation process from A = 93 A 2 /molecule at t = 0 to A = 152 A2/molecule at t = ∞ is explicable solely by the conformational change of cis- → trans-form of the CPP molecules. It has been shown that the change corresponds to the polymorphic transition of CPP-α → CPP-β in three-dimensional crystals, as has been revealed in the hydrolyzability of CPP molecules upon injection of a lipase solution beneath the monolayer.

Skin Contamination by Radioisotopes, (V) Pig Skin Contamination by 239Pu

This paper deals with the contaminabilily and the permeability of Pu with varying soiling lime and acidity of the soiling solution applied to pig skin. It was found that the contaminability of Pu was affected by the formation of colloidal substances in soiling solution, as in the case of Pm, Sb, Po and U, described previously. It was also found that 0.05% of the Pu penetrated through the pig skin with pH 1 soiling solution after 60 min.

Desorption of Carrier-free 60Co, 144Ce and 147Pm from Charcoal Surfaces by Water and Sodium Dodecyl Sulfate Solution

固体表面の放射性粉体汚染およびその除去実験に用いる放射性粉体として, 放射性同位体を吸着した活性炭を用いる可能性を調ベる目的をもって, これに必要な実験的条件を検討した。放射性粉体の除去実験によく用いられる水, およびドデシル硫酸ナトリウム (SDS) 水溶液で洗っても脱離しない条件を, 無担体の60Co, 144Ce, および147Pmについて調ベた。その結果, 粉体除染実験に水を除染剤として用いるときには60Co, 臨界ミセル濃度 (CMC) 以下のSDS溶液を用いるときは144Ce, および147Pmが適していることが知られた。CMC以上の濃度のSDS溶液を除染剤に用いる粉体汚染実験用には, どの同位体も完全によくはなかった。これらの実験から, 粉体汚染試料として活性体に吸着させて用いられる同位体は, その粉体の除染条件によってきめられるべきことが実験的に示された。固体表面の放射性粉体汚染およびその除去実験に用いる放射性粉体として, 放射性同位体を吸着した活性炭を用いる可能性を調ベる目的をもって, これに必要な実験的条件を検討した。放射性粉体の除去実験によく用いられる水, およびドデシル硫酸ナトリウム (SDS) 水溶液で洗っても脱離しない条件を, 無担体の60Co, 144Ce, および147Pmについて調ベた。その結果, 粉体除染実験に水を除染剤として用いるときには60Co, 臨界ミセル濃度 (CMC) 以下のSDS溶液を用いるときは144Ce, および147Pmが適していることが知られた。CMC以上の濃度のSDS溶液を除染剤に用いる粉体汚染実験用には, どの同位体も完全によくはなかった。これらの実験から, 粉体汚染試料として活性体に吸着させて用いられる同位体は, その粉体の除染条件によってきめられるべきことが実験的に示された。