Qualitative and quantitative analysis of new alkyl amide arginine surfactants by high-performance liquid chromatography and capillary electrophoresis.

A protocol for the qualitative and quantitative analysis of novel arginine-based cationic surfactants using HPLC and CE was studied and compared. The optimization of the analytical conditions was carried out through a systematic variation of the experimental parameters such as mobile phase, eluent conditions, ion pairing and amount of sample for HPLC, and type of buffer, ion strength, type and amount of organic solvent, sample injection time, applied voltage and column washing and conditioning for CE.

Note: microbial resistance of wool fabric treated with bis-Quats compounds.

In this paper, the antibacterial activity against Bacillus pumilus, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa of the wool fabrics treated with new antimicrobial bis-quaternary surfactants, DABK and DABB, is studied. The activity was established on the basis of the agar diffusion and protective antibacterial test results and on the basis of scanning electron microscopy (SEM) observation. The results were compared with the HTAB, a monoquaternary surfactant of conventional use. The results from the agar diffusion and protective antibacterial tests do not enable us to confirm whether these compounds are potentially useful antimicrobial agents for the protection of textiles. However, SEM observations show clearly the efficacy of these compounds to protect the wool fabrics against the micro-organisms. SEM has been a useful technique for the assessment of antibacterial activity in textiles.

Reactivity of hair cystine in microemulsion media.

Synopsis Reduction of keratin cystine by thioglycolic acid incorporated in microemulsions of the water/sodium dodecilsulphate/n-pentanol/n-dodecane system has been determined. The results obtained have been interpreted in relation to the properties of the reaction media. Microemulsions with constant oil-to-surface active mixture weight ratios (R(o/s)) and different concentrations of water were chosen as reaction media. At low water concentrations a steep increase in reactivity with the increase of water was observed at all values of R(o/s). However it was more pronounced the higher the oil content. A relation between maximum cysteine formation and percolative behaviour of the microemulsion was found at high R(o/s) values.

Influence of microemulsion structure on cystine reactivity with keratin fibres.

Summary The activity of thioglycolic acid, incorporated in a microemulsion, towards cystine residues present in keratin proteins has been investigated. In an attempt to relate the structural state of the microemulsions to cystine reactivity, an appropriate model system showing a large microemulsion domain with diverse structures was chosen. The realm of preferentially hydrocarbon-continuous microemulsion-type media was found to induce the highest activity.

Surface active molecules: preparation and properties of long chain n-acyl-l-alpha-amino-omega-guanidine alkyl acid derivatives.

Synopsis A new route for the synthesis of long chain N(alpha)-acyl-l-alpha-amino-omega-guamdine alkyl acid derivatives, with cationic or amphoteric character has been established. The general formula of these compounds is shown below. A physico-chemical and antimicrobial study of these products as a function of the alkyl ester or sodium salt (R), the straight chain length of the fatty acid residue (x) and the number of carbons between the omega-guanidine and omega-carboxyl group (n) has been investigated. The water solubility, surface tension, critical micelle concentration (c.m.c.) and minimum inhibitory concentration (MIC) against Gram-positive and Gram-negative bacteria (including Pseudomonas) has been determined. Dicyclohexylcarbodiimide has been used to condense fatty acids and alpha-amino-omega-guanidine alkyl acids. In these conditions protection of the omega-guanidine group is not necessary. The main characteristic of this synthetic procedure is the use of very mild experimental conditions (temperature, pH) to form the amide linkage which leads to pure optical compounds in high yield in the absence of electrolytes. The results show that some structural modifications, particularly the protection of the carboxyl group, promote variations of the surfactant and antimicrobial properties. Only those molecules with the blocked carboxyl group (cationic molecules, where R = Me, Et or Pr) showed a good surfactant and antimicrobial activity. When the carboxyl group was unprotected (amphoteric molecules, where R = Na(+)) the resulting compounds were inactive.