A rapid and highly specific method for the determination of cis-vaccenic acid content in plant lipids by mass chromatography has been developed. Two calibration curves were obtained from the mass chromatography of several standard mixtures containing known amounts of dimethyl disulfide adduct (DMDSA) of methyl cis-vaccenate and DMDSA of methyl oleate. The content of cis-vaccenic acid in standard mixtures was proportional to the values calculated from the peak areas of characteristic ions due to the fragmentation of DMDSA of these esters. A mixture of fatty acid methyl esters prepared from plant total lipids was subjected to a reaction with dimethyl disulfide in the presence of I2 as the catalyst for 30min. After removal of contaminating by-products from the reaction products by thin-layer chromatography, the purified DMDSA fraction of methyl monoenoates was introduced into a gas chromatograph-mass spectrometer. This method has been found applicable to the determination of cis-vaccenic acid content in naturally-occurring lipids, such as chlorella, parsley seed, soybean, and maturing Mallotus japonicus seed lipids.
The antiredeposition of oily soil by Zeolite has been studied under various aqueous conditions, sodium dodecyl sulfate, sodium silicate, sodium carbonate, sodium carboxymethyl cellulose, sodium sulfate and a synthetic detergent. Oleic acid and oleyl alcohol were used as model substances of oily soil. The reflectivity of cotton cloth to which the oily soil adhered was identical with the original, in spite of the addition of Zeolite. In the case of nylon cloth, reflectivity increased with the amount of Zeolite added. That is, the amount of oily soil adhering to the nylon cloth surface decreased with the amount of Zeolite. Thus, in the case of nylon, the antiredeposition of oily soil was concluded due to the Zeolite.
The adsorption equilibria of benzene derivatives (phenol, benzoic acid, nitrobenzene, and aniline), 1-hexanol, 1-butanol, 1-heptanoic acid, and valeric acid on carbon black in aqueous solutions were studied. The carbon black used as the adsorbent was Electronic Conductive Carbon Black (Lion Akzo Co.) treated with nitric acid (B) or hydrogen (C). The surface acidity of carbon black B was large, but that of carbon black C, small. The adsorption isotherms were in good agreement with the Freundlich-type isotherm. The amounts of organic compounds adsorbed increased with decreasing solubility in water. The amount of phenol adsorbed was very large and its solubility, large. To investigate the influence of the ionization of phenol, the amounts of phenol, benzoic acid, and aniline adsorbed on modified carbon blacks were measured for their solutions varying widely in pH. The amounts of phenol and benzoic acid adsorbed on carbon black C decreased with increasing pH, but the amount of aniline adsorbed onto it decreased with decreasing pH. Thus, the amount of phenol, benzoic acid, and aniline adsorbed decrease with an increase in the amount of adsorbate ionized. The pKa value of phenol was larger than those of other organic compounds. Consequently, it is thought that phenol is adsorbed specifically owing to its large pKa. The adsorption character of an organic compound can be predicted on the basis of its solubility and pKa.
The hardness of a mixture prepared from a heat-dissolved solution of a wax and oil for cosmetics varied with the properties of the oil used. These properties were thus examined so as to clarify the mechanism for variation in hardness. The hardness of solid paraffin-oil mixture was found to be closely related to the solubility (g/100g solution) of solid paraffin in the oil used. That is, a solid paraffin-oil mixture comprising the oil with a lower solubility of solid paraffin gave rise to a higher degree of hardness. For a carnauba wax-oil mixture, the same relationship between hardness and solubility as that of the solid paraffin-oil mixture was found. Consequently, in the preparation of mixtures of a wax and various oils, their hardness can be predicted on the basis of the solubility of wax in the oils, which in turn can be estimated from the solubility parameters of the wax and the oil, as well as from the oil molecular weights.